Create a shared account pool for end-to-end tests instead of creating and seeding blockchain accounts before each test

[kbeker]

This issue is related with #744 and #970.
To shorten duration on SCI initiation tests should be run together. There should be created new file where would be whole mechanizm to initialize SCI instance and pass it to all api-e2e tests (instead of initializing SCI every api-e2e test).

• Change all api-e2e-tests from based on function to based on class, where every test will be a method in this class.
• Modify @count_fails decorator, It should be a class from which every api-e2e-tests class will inherit. It still should work in the same way.
• It still should be a possibility to run each api-e2e-test without running all others tests in one time
• It still should be a possibility to run tests without initializing full SCIBaseTest
• Create main class for all api-e2e-tests together.
• Init SCIBaseTest in the beginning of whole class
• Pass instance of SCIBaseTest to every api-e2e-test
• Run all tests one by one starting from UC1 to UC5

Remember that not only:

• api-e2e-force-payment.py
• api-e2e-force-accept-or-reject-results-test.py
• api-e2e-additional-verification-test.py
  have been modified to get all keys from SCIBaseTest. Other tests left also need to be modified to retrieve keys from SCIBaseTest class.

Whole SCI mechanism for creating accounts and checking transaction is already done in #995.

[PaweuB]

Pivotal:
https://www.pivotaltracker.com/story/show/162753858

[cameel]

Could you explain the proposed solution in more detail? From this description I have no idea how api-e2e-tests.sh is going to look like. And who is supposed to run it and when.

[kbeker]

@cameel I edited issue to my idea how it should be done.