added helpers for chart selection tag to determine which charts user selected
Merge branch 'master' into graphs

My branch is behind master by multiple commits, and in order for me to use current_course helper method (which has been corrected in another merged branch), I need to merge.
changed metrics show view to only rendered graphs that user selected in preceding form
removed unused files and commented-out tests, spaced out graphs on view page
Merge pull request #29 from zrivest/graphs

Graphs