update "scribe-common" includes to include "src"

This syntax is compatible with CommonJS as well as RequireJS.

As described in: http://git.io/CGL0Lg
use "scribe-common"'s `element`

Now we can remove the `src/api/element.js` file since
"scribe-common" offers the exact same helper functions.
examples: fix AMD path for scribe-common
test: fix AMD path for scribe-common
Merge pull request #217 from Automattic/update/scribe-common-src-path

update "scribe-common" includes to include "src"