fix(ngx-translate): updated build to fix "Unexpected token import err…

…ors"

BREAKING CHANGE: I've finally taken the time to update the entire build system for the library using ng-packagr instead of my own custom webpack config.
I've also added support for rxjs lettable operators at the same time, it means that I've been forced to add a peer dependency for RxJS >= 5.5.2. and I've updated the minimum Angular version to >=5.0.0.
The library should be much smaller (from ~80ko to ~20ko for the umd bundle!) and it now supports ES2015 to be tree-shackable which might drop the size even more. 
It should also fix the "Unexpected token import errors" that some people were experiencing.
Unfortunately this might be breaking people since the peer dependency have changed and that's why it's a new major version.

Closes #724, Fixes #581

.gitignore

@@ -18,6 +18,8 @@ npm-debug.log
 coverage
 *.metadata.json
 bundles
+build
+dist
 
 #################
 ## JetBrains

.travis.yml

@@ -1,28 +1,17 @@
 language: node_js
-
 cache: yarn
-
 sudo: false
-
 notifications:
   email: false
-
 node_js:
-  - '7'
-
-branches:
-  except:
-    - "/^v\\d+\\.\\d+\\.\\d+$/"
-
+  - '8'
 before_install:
   - export CHROME_BIN=chromium-browser
-
-before_script:
-  - npm prune
-
 after_success:
-  - npm run semantic-release
-
+  - yarn semantic-release
+branches:
+  except:
+    - /^v\d+\.\d+\.\d+$/
 before_script:
   - export DISPLAY=:99.0
-  - sh -e /etc/init.d/xvfb start
+  - sh -e /etc/init.d/xvfb start

README.md

@@ -1,12 +1,12 @@
 # @ngx-translate/core [![Build Status](https://travis-ci.org/ngx-translate/core.svg?branch=master)](https://travis-ci.org/ngx-translate/core) [![npm version](https://img.shields.io/npm/v/@ngx-translate/core.svg)](https://www.npmjs.com/package/@ngx-translate/core)
 
-The internationalization (i18n) library for Angular 2+.
+The internationalization (i18n) library for Angular.
 
 Simple example using ngx-translate: https://plnkr.co/edit/WccVZSBM0rUgq2sXSUbe?p=preview
 
 Get the complete changelog here: https://github.com/ngx-translate/core/releases
 
-**This is the documentation for the 6.x version, if you're using 5.x or less, refer to [this document](https://github.com/ngx-translate/core/blob/fb02ca5920aae405048ebab50e09db67d5bf12a2/README.md).**
+**This is the documentation for the 6+ version, if you're using 5.x or less, refer to [this document](https://github.com/ngx-translate/core/blob/fb02ca5920aae405048ebab50e09db67d5bf12a2/README.md).**
 
 * [Installation](#installation)
 * [Usage](#usage)

config/webpack.test.js

@@ -64,7 +64,7 @@ module.exports = {
         // fix the warning in ./~/@angular/core/src/linker/system_js_ng_module_factory_loader.js
         new webpack.ContextReplacementPlugin(
             /angular(\\|\/)core(\\|\/)@angular/,
-            helpers.root('./src')
+            helpers.root('src')
         ),
 
         new LoaderOptionsPlugin({