Consolidated coverage report generation into one rake command.
Added diff coverage reports using diff-coverage tool.
Clean the report directories before each test run,
to ensure we don't get coverage results from a
previous test run.
Added diff-cover as a requirement (installed from github)
Fixed bug in tests.rake in which rm would be called with no args.
Updated to current tag of diff-cover
Merge branch 'master' into will/diff-cover-integration
Added diff coverage printout to rake coverage command
Added warning message when no coverage information found.
Added comments to tests.rake
add exporting of 'about' content as well as adding unit test checks
Merge pull request #74 from edx/fix/cdodge/about-elements-not-exporting

[STUD-244] add exporting of 'about' content as well as adding unit test checks
Merge pull request #68 from edx/will/diff-cover-integration

Will/diff cover integration
Re-insert "if in course" check for displaying paragraph about forums.

Accidentally got removed in pull request 13.
Merge pull request #78 from edx/victor/fix-help-button

Re-insert "if in course" check for displaying paragraph about forums.