Add pkg directory to .gitignore

Now that the Bundler gem tasks have been added to the rake file, we
don't want to accidentally commit anything in the `pkg` directory.

Change-Id: Ia199ce9ae07fa56362103ad4ec40a20f72b92119
Reviewed-on: http://gerrit.causes.com/37225
Tested-by: jenkins <[email protected]>
Reviewed-by: Shane da Silva <[email protected]>

Author: Shane da Silva

.gitignore

@@ -1,5 +1,6 @@
 .bundle
 Gemfile.lock
+/pkg
 
 # YARD
 /doc