Stabilization of tests for howitzer examples

[evgeniyvlb]

Need to stabilize tests for howitzer examples on travis CI to avoid job's failings

[romikoops]

• [x] 1. Rspec, Turnip and Cucumber test suits must be executed in sequence

[romikoops]

• [x] 2. Check tests are executed randomly each time in each suite

[romikoops]

• [x] 3. Review all tests and make sure we do not create categories for test where we can use default category

[romikoops]

• [x] 4. Review tests where categories are created and make sure they clean up categories even if test is failed.

[romikoops]

5. Execute each full test suite and review which test are still not stable, except network errors, and some specifi errors, like blank page and etc.