Added a reset method to the facade
Don't include_once the definitions

We can't load definitions after resetting the facade instance if we
don't change this.
Updated the tests to use the new reset method

This means that our tests no longer depend on phpunit's run in separate
process stuff so should work better with a global phpunit install.
Added reset docs
Merge pull request #293 from GrahamCampbell/reload

Added The Ability To Re-Create The Underlying Factory Instance
Make the getFaker method public
Added tests for the getFaker method
Updated the docs for the public getFaker method