Remove Application dependency in RoleManager.

Remove the Phansible\Application dependency in Phansible\RoleManager as
is not being used for nothing.
Remove som "use" statements not being needed.
Rewrite RoleManager tests to improve readability

Remove existing dependencies between the Phansible\RoleManager
test and some roles. This way modifying this tests will not break
RoleManager tests.
Remove BaseRole test

Abstract classes should not have tests.
In fact the Roles should have their tests if that is important at all.
Remove strange _assets folder from tests.
Remove $app parameter not being used in roles provider.
Merge pull request #149 from naxhh/improve-tests

Improve tests readability a bit