Various commands for handling vendor dependencies for your application

The VendorCommands plugin for Pyrus operates on the `vendor` directory within
your local application directory. To install this plugin use 
`php pyrus.phar install -p Pyrus_VendorCommands-alpha`

The vendor-update command scans the package.xml file for dependencies and will
install them into the local vendor/ directory of your application.

Example: `pyrus vendor-update`