Fix docstring
Fix for self.cycles[-1] throwing exception if empty
Moved Apdex stuff to its own module

Encapsulation += 1
Maintenance += 1.  Now it's easy to test, so test have been added.
Also, less argument passing == cleaner code
Merge pull request #118 from sjbrown/add-apdex-mod

Moved Apdex stuff to its own module
Merge pull request #119 from sjbrown/minor-fixes

Minor fixes