Addition of ROLESPEC_ANSIBLE_OPTS variable and bugfix for test names

Hello,

This pull request makes the following changes:
-    adds a new variable called `ROLESPEC_ANSIBLE_OPTS` which allows you to pass additional options to `ansible-playbook`. For example, this could be useful to skip certain tags or pass along the vault password
-    fixes a bug where if you have multiple tests that all start with the same name, e.g nginx, nginx-php, and nginx-ssl, then the grep would glob all of them (and fail to run) rather than the one specified with `rolespec -r <role>`

Thanks,

Andrew