Remove lms/lib from sys.path in favore of using it as the module lms.lib
Fix pylint/pep8 errors
Use XBlock handlers for handle_ajax in XModules

Adds xblock handler_url support to the LMS, and makes handle_ajax use
that code.

[LMS-230] [LMS-229]
Merge pull request #1531 from cpennington/lms-xblock-handlers

Use XBlock handlers in the LMS ...