Add error handling facilities
Slight tweaks to formatting style
Typo in ErrorHandlerInterface docblock

Fixed typo and shortened, included FQN in namspace imports up top
Refactor 'new ErrorException' into factory

A pain, but needed for tests (and future configurability).  The
new instantiation of \ErrorException in CmdLineErrorHandler has been
refactored into a factory and wired into the DIC.
Add tests for new CmdLineErrorHandler
Docblock and few formatting issues