composer: Rename package to 'oojs-ui' and require php 5.3.3

The composer name is composed of publisher/package-name (similar
to GitHub paths). To allow easy forking and avoid name clashing,
consistently use 'oojs-ui' as the package name.

This hasn't been tested with PHP 5.3.2. MediaWiki and CSSJanus
both support PHP 5.3.3. and higher. Might as well match that.

Change-Id: Ib021b5524e15b3b3ba65110b6c23d214388a4758
Merge "composer: Rename package to 'oojs-ui' and require php 5.3.3"