Don't truncate osapi_glance_link or osapi_compute_link prefixes

When osapi_glance_link_prefix or osapi_compute_link_prefix is
defined and used to update the links return in API responses, do
not drop the path component of the overriding link prefix.

Change-Id: I290e3f85b94e28d25a54621c1699081cbbf48456
Closes-Bug: 1304099
Check requirements.txt files for missing (used) requirements

Invoke the pip-missing-reqs tool to find packages used by nova but
not explicitly included in its requirements.txt file.

Add simplejson to the requirements to fix the failing check.

Change-Id: Ia90416c613c0acea04f3d4ab4898f550cb702a49
Merge "Don't truncate osapi_glance_link or osapi_compute_link prefixes"
Merge "Check requirements.txt files for missing (used) requirements"