Testing in both live and mock environments

[docsteveharris]

see #161 (although this issue could be better named)

force pytest installation
notes on debugging live from the GAE
distinguish tests for the live environment
filter live tests out of CI

Note from @jongillham

I see the idea here. However I'm not so keen on unit tests that need external dependencies such as a live system to work. It potentially sets a bad precedent for future tests.

I also see the consequence of this test is that by default pyenv now needs -m 'not live' where as ideally testing live should be the exception.

I would prefer that you ripped out the live testing part and we figure out another way to do integration testing on the live or staging deployments.

@harryjmoss & @docsteveharris what are your thoughts on how strict with codebase we should be?