3.4/develop

Fully embraced the composer way of doing things, added requirement of PHP 5.4+, and added some fancy new 5.4 stuff.
I know there was some discussion somewhere (I can't seem to find it right now) about adding a `VENDIR` that points to `vendor`. This could be changed to `VENDIR.'kohana/core' in that case. Is that something we'd like to add in this PR also?