Sometimes we need to run the full test suite without some tests.
Now the new '--skip-list' argument allows us to do it. In order to skip
the desired tests we just need to list the tests in some file and provide
the '--skip-list' argument with the path to the file:
rally verify start --skip-list /path/to/the/file
Also, missing messages about incompatibility of arguments were added.
Change-Id: I882bfacd2e39bed2b54af4092752f642c964975a