Add missing depedency on mock.
Fully specify coverage options.

The coverage testing started to run the MarkupSafe and Jinja2
tests at some point.  Tightening up the testing and coverage options
fixes that.
Remove pip.commands.install reference in tests.

For some reason I was importing install from pip.commands instead
of using the patch.  This commit removes the import and uses the
patched value instead.
Merge pull request #3 from dave-shawley/correct-tests

Correct tests