Ensure JSON headers in Auth Requests

The Content-Type header will be set automatically by the request call
however we should also ensure that we set the Accept header because our
auth plugins only work with JSON.

Change-Id: Ib3badd70f4fa32d400565c39a072db547d86037e
Use `HttpNotImplemented` in `tests.v3.test_trusts`

Since we are moved to usage exceptions from oslo, `HTTPNotImplemented`
was renamed to `HttpNotImplemented`, so we need to change usage of this
exception in tests.

Related to blueprint common-client-library-2

Change-Id: I51f6593ebb86267dad7086d4862a135743f2de7f
Updated from global requirements

Change-Id: Icc5f3cdf0cfe9a1566ff5efafc85471381e3622d
Merge "Use `HttpNotImplemented` in `tests.v3.test_trusts`"
Merge "Ensure JSON headers in Auth Requests"
Merge "Updated from global requirements"
Don't use generic kwargs in v2 Token Generation

We need to allow for people adding other stuff to the tokens however it
shouldn't be available in the standard case where for example a misspelt
variable would be propagated.

This is in line with how v3 is going to handle this same scenario.

Change-Id: I1aad17893574ebc7c3a6b84f4d6ba1cd27932158
Closes-Bug: #1307278