PEP-8 cleanup of utils file.  Remove unused logger.
Remove unused import from views.  Use RequestContext subclass from icommons_common project to expire sessions after a certain period of inactivity.
Use renamed session inactivity request context subclass when instantiating shared context variable.
Add updated session inactivity expiration setting to canvas_sdk_settings dictionary in production.
Revert to original Vagrantfile
Match egg version of canvas-python-sdk in lti_tools base requirements with requirement listed as dependency of icommons_common.
Merge pull request #106 from Harvard-University-iCommons/feature/session_expiration

Feature/session expiration
Bumped the version of django-icommons-common to 1.4
Merge branch 'develop' into feature/sections_primaryfix