Initial empty skeleton to display list of plugins

Define the initial project skeleton with:
- Buck build
- AngularJS HTML and JS
- X-GerritAuth expansion for REST API calls

As demo of the skeleton working well, the index.html display the
list of currently installed plugin invoking the Gerrit REST API
/plugins/?all

Change-Id: I122c37b8486609363bc92222d60153266c92e6d0