Added two new bash shell scripts to wrap up the process of packaging or

pubishing the extension via vsce. Added these files to .vscodeignore so that
they will not themselves be released.

Both scripts first remove any existing package archives (*.vsix) and then run
the package or publish command.

In future, adding additional steps to the release process will be as simple as
updating these scripts.

.vscodeignore

@@ -10,3 +10,6 @@ node_modules/**
 .nyc_output/**
 coverage/**
 keep/**
+package
+publish
+

package

@@ -0,0 +1,4 @@
+#!/bin/bash
+rm file-header-comments*.vsix
+vsce package
+

publish

@@ -0,0 +1,4 @@
+#!/bin/bash
+rm file-header-comments*.vsix
+vsce publish
+