add roles when using constructor injection

Bread::Board::ConstructorInjection->new(
  class => 'Foo',
  roles => ['Bar'],
)

the benefit of this is to allow us to modify classes that we may not have
control over modifying the source of at runtime.

Signed-off-by: Caleb Cushing <xenoterracide@gmail.com>

note: state of this is basic functionality, probably needs many more tests, and of course docs. Should this be able to work on any of the other service types? any thoughts on additional error handling? or anything else?