possibility to change tests order was added:

* you can use `"order": "tryfirst"` to move test to the beginning of test queue
* you can use `"order": "trylast"` to move test to the end of test queue
tests ordering was refactored:

ordering in more pythonic way now
fix: removed function was replaced with correct object
Merge pull requet #3 from 'features/tests-ordering'

possibility to change tests order was added