Small improvements of integration tests

* Corrected bugs in cluster config test;
* Corrected file README.rst;
* Changed file common_parameters.py;
* Changed file common_config.py.sample;
* Changed file hdp_config.py.sample;
* Changed file vanilla_config.py.sample.

Change-Id: I8bf5292e7dbb324d99590bcbca0f1a79a9d0b765