OS access credentials processing added

What is done:
- os access credentials retriving from POST request body on wsgi
  controller for TestRun entity added;
- needed environment variables setting added in nose StoragePlugin;
- settuping process for HealthCheck updated;
- integration tests for ostf adapter updated;
- unit tests also updated;
- change was tested on deployed env.

Change-Id: I96580e4e59db0314a75c27f2dda49cf268b05b95
Closes-Bug: #1281838
Merge "OS access credentials processing added"