Format code.
Merge pull request #14 from Hywan/format_code

Format code
Use composer components

Packages are now fully compliant with composer's API

We can use composer downloaders
Add support for package names in install command

The full pattern is [pecl/]<package>[-<stability>][@<version>]
Fix tests
Update info command and fix package pattern
Fix tests
Add git support
Fix git download