Something behind webpack requires python2 :(

```
       Installing node modules
       npm error code 1
       npm error path /tmp/build_355054ab/node_modules/node-sass
       npm error command failed
       npm error command sh -c node scripts/build.js
       npm error Building: /tmp/build_355054ab/.heroku/node/bin/node /tmp/build_355054ab/node_modules/node-gyp/bin/node-gyp.js rebuild --verbose --libsass_ext= --libsass_cflags= --libsass_ldflags= --libsass_library=
       npm error gyp info it worked if it ends with ok
       npm error gyp verb cli [
       npm error gyp verb cli   '/tmp/build_355054ab/.heroku/node/bin/node',
       npm error gyp verb cli   '/tmp/build_355054ab/node_modules/node-gyp/bin/node-gyp.js',
       npm error gyp verb cli   'rebuild',
       npm error gyp verb cli   '--verbose',
       npm error gyp verb cli   '--libsass_ext=',
       npm error gyp verb cli   '--libsass_cflags=',
       npm error gyp verb cli   '--libsass_ldflags=',
       npm error gyp verb cli   '--libsass_library='
       npm error gyp verb cli ]
       npm error gyp info using [email protected]
       npm error gyp info using [email protected] | linux | x64
       npm error gyp verb command rebuild []
       npm error gyp verb command clean []
       npm error gyp verb clean removing "build" directory
       npm error gyp verb command configure []
       npm error gyp verb check python checking for Python executable "python2" in the PATH
       npm error gyp verb `which` failed Error: not found: python2
       npm error gyp verb `which` failed     at getNotFoundError (/tmp/build_355054ab/node_modules/which/which.js:13:12)
       npm error gyp verb `which` failed     at F (/tmp/build_355054ab/node_modules/which/which.js:68:19)
       npm error gyp verb `which` failed     at E (/tmp/build_355054ab/node_modules/which/which.js:80:29)
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/which/which.js:89:16
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/isexe/index.js:42:5
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/isexe/mode.js:8:5
       npm error gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:197:21)
       npm error gyp verb `which` failed  python2 Error: not found: python2
       npm error gyp verb `which` failed     at getNotFoundError (/tmp/build_355054ab/node_modules/which/which.js:13:12)
       npm error gyp verb `which` failed     at F (/tmp/build_355054ab/node_modules/which/which.js:68:19)
       npm error gyp verb `which` failed     at E (/tmp/build_355054ab/node_modules/which/which.js:80:29)
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/which/which.js:89:16
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/isexe/index.js:42:5
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/isexe/mode.js:8:5
       npm error gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:197:21) {
       npm error gyp verb `which` failed   code: 'ENOENT'
       npm error gyp verb `which` failed }
       npm error gyp verb check python checking for Python executable "python" in the PATH
       npm error gyp verb `which` failed Error: not found: python
       npm error gyp verb `which` failed     at getNotFoundError (/tmp/build_355054ab/node_modules/which/which.js:13:12)
       npm error gyp verb `which` failed     at F (/tmp/build_355054ab/node_modules/which/which.js:68:19)
       npm error gyp verb `which` failed     at E (/tmp/build_355054ab/node_modules/which/which.js:80:29)
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/which/which.js:89:16
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/isexe/index.js:42:5
       npm error gyp verb `which` failed     at /tmp/build_355054ab/node_modules/isexe/mode.js:8:5
       npm error gyp verb `which` failed     at FSReqCallback.oncomplete (node:fs:197:21)
       npm error gyp verb `which` failed  python Error: not found: python
       npm error gyp Build failed with error code: 1
```

.python-version

@@ -0,0 +1 @@
+2.7.18