remove submodules
update paths to use flattened repo structure
fix conflict with HTMLImports
promote 'mixin' from CustomElements into Platform lang.js
Merge branch 'master' into flattened-repos

Conflicts:
	platform.min.js
	platform.native.min.js
	platform.sandbox.min.js
use flat path for PointerEvents
update maps
Merge pull request #19 from Polymer/flattened-repos

Flatten repos