adding case priority
Add visibility of case priority to run tests and display results screens
Add ability to sort by case priority on run tests and display results screens
Add case priority visibility and sorting to the Manage Test Cases screen
Add test coverage for case priority to test_forms.py
Add priority attribute to test cases in fixture_gen.py
Update sass for manage cases, run tests and view results to incorporate priority
Update generated css file
Merge pull request #35 from bobsilverberg/1.4.8

Add a priority to test cases
add results filtering by priority and tester
adding sorting by priority in the multiselect suite and tag screens

also add filtering by tester in results