Feature: enable binding of fallback function if flash is unavailable

The PR also includes some changes I made to the Gruntfile (needed a server to develop on), let me know if you would like me to re-open the PR with only the pertinent changes to the directive.

The fallback function is optional. To enable it, you would use `clip-click-fallback="fallback(copy)"`

If the function definition accepts an argument named `copy`, copy would be the string returned from the `clip-copy` attribute.