chore(Rakefile): generate version.json

Changes 'rake version' to output a version.json file which
contains the structured version info which can be used in other tools.

Author: jbdeboer

Rakefile

@@ -112,9 +112,15 @@ task :minify => [:init, :concat, :concat_scenario] do
 end
 
 
-desc 'Generate version.txt file'
+desc 'Generate version.txt and version.json files'
 task :version => [:init] do
   `echo #{NG_VERSION.full} > #{path_to('version.txt')}`
+  `echo '{
+  "full": "#{NG_VERSION.full}",
+  "major": "#{NG_VERSION.major}",
+  "minor": "#{NG_VERSION.minor}",
+  "dot": "#{NG_VERSION.dot}",
+  "codename": "#{NG_VERSION.codename}"\n}' > #{path_to('version.json')}`
 end