Enhance support for Bandcamp and Vine URLs.

We provide special handling for Bandcamp and Vine URLs that generates code
for Bandcamp and Vine players.
Update to Twitter URL pattern.

Currently we only handle URLs like:

    https://twitter.com/JonathanAquino/status/332855223402000385

This patch also allows URLs like:

    https://twitter.com/JonathanAquino/statuses/332855223402000385

which are also valid.
Make Essence autoloader not attempt to load non-Essence classes.

Here we make sure that the Essence autoloader only attempts to load classes that
begin with Essence\...