(GH-12) Add Gulp task to bump the package version

This commit adds the required modules and gulp task to bump the package.json
version via Gulp.  This will be used in automated testing and publishing tasks.

Author: glennsarti

client/gulpfile.js

@@ -3,6 +3,8 @@ var gulp = require('gulp');
 var del = require('del');
 var runSequence = require('run-sequence');
 var exec = require('child_process').exec;
+var bump = require('gulp-bump');
+var args = require('yargs').argv;
 
 // The default task (called when you run `gulp` from cli) 
 gulp.task('default', ['build']);
@@ -33,3 +35,31 @@ gulp.task('build', function (callback) {
   runSequence('clean','copy_language_server','build_extension',callback);
 })
 
+gulp.task('bump', function () {
+    /// <summary>
+    /// It bumps revisions
+    /// Usage:
+    /// 1. gulp bump : bumps the package.json and bower.json to the next minor revision.
+    ///   i.e. from 0.1.1 to 0.1.2
+    /// 2. gulp bump --version 1.1.1 : bumps/sets the package.json and bower.json to the 
+    ///    specified revision.
+    /// 3. gulp bump --type major       : bumps 1.0.0 
+    ///    gulp bump --type minor       : bumps 0.1.0
+    ///    gulp bump --type patch       : bumps 0.0.2
+    ///    gulp bump --type prerelease  : bumps 0.0.1-2
+    /// </summary>
+
+    var type = args.type;
+    var version = args.version;
+    var options = {};
+    if (version) {
+        options.version = version;
+    } else {
+        options.type = type;
+    }
+
+    return gulp
+        .src(['package.json'])
+        .pipe(bump(options))
+        .pipe(gulp.dest('.'));
+});

client/package.json

@@ -126,6 +126,8 @@
     "vsce": "^1.18.0",
     "mocha": "^2.3.3",
     "gulp": "^3.9.1",
+    "gulp-bump": "^2.7.0",
+    "yargs":"^8.0.1",
     "del": "^2.2.2",
     "run-sequence":"^1.2.2",
     "@types/node": "^6.0.40",