Use tempest.lib code in tempest

Now that tempest_lib code is copied back into tempest, stop using
tempest_lib in tempest, and start using the copied code.

Remove the dependency to tempest_lib from requirements, and drop
the script to use tempest_lib in tempest. Add os-testr to the
test-requirements.

Partially implements bp tempest-lib-reintegration

Change-Id: I21ab5fe6349f72c98ac9f960a29bf62e813f8b1b
168 files changed