Rename assertRaisesRegexp to assertRaisesRegex

[migueldvb]

This change was introduced in python 3.2

[coveralls]

Coverage decreased (-0.4%) to 92.214% when pulling 6170b96 on migueldvb:tests into 695bdfe on andycasey:master.

[vsudilov]

This breaks the build for python27, also I'm not sure what problem this is trying to address since the last build of master succeeded on python34: https://travis-ci.org/andycasey/ads/builds/308991419

[coveralls]

Coverage decreased (-0.4%) to 92.214% when pulling 1eba43f on migueldvb:tests into 695bdfe on andycasey:master.

[coveralls]

Coverage remained the same at 92.659% when pulling 583413c on migueldvb:tests into 695bdfe on andycasey:master.

[migueldvb]

Oh, I have replaced the assertion by the six alias that is available on python 2.7. This gets rids of DeprecationWarnings on python > 3.1.

[vsudilov]

LGTM thanks; want to fix the SSL errors in py27 too? ;) https://travis-ci.org/andycasey/ads/jobs/309099466

[migueldvb]

I was looking at those travis errors. I have seem something like that before in old 2.7 releases but this is with 2.7.13... I'll take a look.

[vsudilov]

I strongly suspect it is this:
gabrielfalcao/HTTPretty#242

where the accepted solution is to change to a different mocking library.

No worries if you'd rather not get into that