DRY when building libraries paths.
Replace self:: in favor of CakeResqueShell:: to be nice with PHP 5.3.
Generate 'worker' command once.
Merge pull request #40 from bar/cakeresqueshell-optimizations

Cakeresqueshell optimizations.
add 'CakeResque.Status.lib' config option

so that people using Composer to install the CakeResque plugin itself can specify an alternative path to the appropriate vendors directory.

Signed-off-by: Joshua Paling <joshua.paling@gmail.com>
Merge pull request #42 from joshuapaling/feature-status-lib-config

add 'CakeResque.Status.lib' config option
added Folder::isAbsolute