Require testrepository>=0.0.18

To help with debugging, quoting from upstream:

 `run` now accepts `--isolated` as a parameter, which will cause
 each selected test to be run independently. This can be useful
 to both workaround isolation bugs and detect tests that can
 not be run independently.

Change-Id: I168700457566067cc7389d290a2d7ef4e87ba8a2
Add posix_ipc as requirement

This is going to be needed for Oslo lockutils.

Change-Id: I472d22c7807dedf1ee433cc7eea9aafe0772b5ff
Blueprint: lockutils-posix-ipc
Add oslotest library

Allow projects to start using the oslotest library instead
of copying test base classes and fixtures out of the
incubator.

Change-Id: Ib198e013462ad07d29347aa9171f03f5803c7396
Merge "Add oslotest library"
Merge "Require testrepository>=0.0.18"