Add some additional "Bash statements".

This adds:
* `chown` to complement `chmod`,
* `yum`, `rpm`, and `pacman` to complement the aptitude commands for other distros
* and `php` and `composer` to complement `node` and `npm` and family.

This list can never be complete, but this should round out some fairly common cases.
Merge pull request #9 from nubs/master

Add some additional "Bash statements".