major update in tests

changes in model_tests:
- - - all methods received docstrings
- - - rewritten all methods (too much to describe, read docstrings)
- - - added update method

changes in admin template:
- - - added support for template editing

changes in testsview.py:
- - - lots of changes in all views;
- - - all views received docstring;
- - - added update view;

changes in tests.js:
- - - lots of changes in all functions
- - - added test editing