Update foundation.interchange.js

Change regex so it only matches images
Update foundation.interchange.js

Use regex literal to remove need for regex var
New regex tests for an image extension at the end of path
Update foundation.interchange.js

Use Zurb reggex
Merge branch 'interchange-regex' of https://github.com/clyates/foundation into clyates-interchange-regex

Conflicts:
	js/foundation/foundation.interchange.js