ziafazal/api-fix-bug-progress-tab: fix progress

Fixed progress value by using total modules in the course as
denominator.

variable names changes and login for total_actual_completions

efficient way to load leaf modules

 and added required settings to tests
Merge pull request #186 from edx-solutions/ziafazal/api-fix-bug-progress-tab

ziafazal/api-fix-bug-progress-tab: fix progress