Migrate unit test to testtools

Additional changes:
* Removed testing framework for MuranoPL since it was based on Nose
* Made test_log run only on Linux hosts
* Every testcase is now required to have proper setUp method

Change-Id: I86ee5ec487019c2d1b77f0fd34f748cf9c6412a0
Implements: blueprint migrate-murano-ut-to-testtoools
Merge "Migrate unit test to testtools"