add support for a --full command-line option

Add support for a --full command-line option. This indicates that a full build is requested.
Fixes to have a clean package after the latest breaking changes from bleeding
edge.

BUG=

Review URL: https://chromiumcodereview.appspot.com//12052035
Update .gitignore
Merge pull request #315 from devoncarew/master

Modify lib/component_build.dart to add support for a --full command-line arg
eliminate confusing local variable 'json' with imported library