CB-7199 control git/npm using platform.js

www will default to git
if you want a platform to use git, just add source:git to its platforms.js section
Adds basic support for ripple platform
Bunch of fixes:
* Remove unnecessary functionality from ripple_parser
* Change git uri for ripple platform
* Uncomment platform functionality for plugman
ripple platform snapshot loading support
makes Ripple to be listed as available platform
Specify that ripple should use git