Codeception formatting fix

Formatting fix, tabs to 4 spaces. I looked through the code and there are some othe places where tabs and spaces are used together so will fix it later) This one PR also must be merged after PR about unit-tests https://github.com/Codeception/Codeception/pull/198 because somehow it includes (i did something wrong - did not switched back from that branch (unit-tests PR) and just created this new based on that branch) new additions according that PR.