Move setting redhat credentials to get_empty_environment function
READY_STATE of an environment: empty + release settings
there is no need to snapshot environment in setup_environment method
make empty snapshot in get_empty_environment function
pep8 fix
Remove test for redhat release downloading It is a part of configuration procedure
Remove unused code from base_node_test_case
Merge pull request #1484 from Mirantis/int-test-redhat-support

Integration tests redhat support
Update makesystem for fuel-main repo