Feature/increase code coverage (#39)
* Changed step function names to be suitable for testing
* Added tests for custom type steps.
* Removed unnecessary imports
* Removed unnecessary imports
* Modified some steps a bit to be more flexible for testing without using patch
* Added MockedStep and MockedWorld classes
* Added new unit tests about @given steps
* Added __init__.py into the tests/steps directory
* Fixed string formatting on one of the tests
* Fixed some of the class initiation parts on mocks. Also added self.stash on class init
* Removed unnecessary imports
* Added few more unit tests for steps
* Added one more step test case.
* Enabled coverage badge on README.md
* Added few more tests
* Bumped patch version by 1
* Removed unnecessary imports
* Added few more unit tests
* Fixed one of the steps where it was not failing on must cases
* Fixed 2 unit tests and add another one.
* Fixed a step where must and must not is not processed properly
* Added 4 more unit tests and fixed 1 unit test
