Add HTTPretty to test requirements.

HTTPretty is a means of stubbing HTTP calls that is library independent.
It is MIT licensed and can be found: https://github.com/gabrielfalcao/HTTPretty
for examples of its use. Development is active with the 0.6.2 version
released only a week ago.

I think an approach like this is simpler than the current means of
stubbing requests or HTTPlib, more explicit in what sites requests are
being made to and it will allow a common test layout/format between
httplib, requests or whatever other http library is being used.

Change-Id: I01f291d324fd9902a4e728775019fe3c43bcf61e
Require later version of stevedore

Changes requirement for stevedore to be >=0.10 because
that version of stevedore has the ability to propagate
exceptions up through the map call which is required for
some of the Nova V3 API extensions to work properly

Change-Id: Ic2316e1f0cba28521950f3313652514dd7484378
Remove Ming and SpiderMonkey

Ceilometer dropped their usage since https://review.openstack.org/#/c/33290/

Change-Id: I4421d0b38d44d952261f537187c14a5f2217f0f9
Signed-off-by: Julien Danjou <julien@danjou.info>
Merge "Add HTTPretty to test requirements."
Merge "Remove Ming and SpiderMonkey"
Merge "Require later version of stevedore"