Install test-requirements with main install

To reduce the total number of invocations necessary for pip which isn't
the quickest thing ever (due to needing to evaluate constraints and deps
lists and what is currently installed) combine the main installation of
software with its test-requirements.txt file which should roughly halve
our pip invocations.

Change-Id: Ibcc3264136e66d34a879ad1c90a62e1bb6a84243
1 file changed