Add standalone build for 3.4 series

Merges the 3.3/develop branch up to 3.4/develop and updates the travis and composer configs for 3.4.x - continues kohana/kohana#50
Hmm, but when 3.3.3 will be released, we have two stable branches, 3.2 (stable, but unsupported) and 3.3 (stable + develop branch). 3.4 will have only develop branch. I like the *overview* idea, but wouldn't that be confusing?