Improve test battery stability

Add skip_all function to test header.
Skip many Rosie tests if sqlalchemy not installed.
Avoid Jinja2 version instability.
Skip remote tests if test job host not defined.
t: use new `skip_all` function where applicable
Improve test stability

May skip `cherrypy` dependent tests.
Skip tests properly.
t: improve skip messages
Merge pull request #1102 from matthewrmshin/improve-t-stability

Improve test battery stability