Fix deprecation warning in test_multiprocessing

tests/functional/v1/test_multiprocessing uses psutil to get a list of
processes. The Processor class now uses children() instead of
get_children(); update the test with the current call to eliminate
the deprecation warning.

Change-Id: I83a6bb72b5282d3ab2a3b8e338ee3dc8668d2d53
Do not allow HEAD images/detail

Currently, a HEAD images/detail request goes through the images/{id}
route which leads to a 500 response status.
This HEAD method should be handled separetely in order to return a
405 Method Not Allowed response and suggest GET as an allowed method.

Change-Id: Ic83e819189bcff7c4735af476217a9ed1e4f41b8
Closes-Bug: #1297358
Merge "Fix deprecation warning in test_multiprocessing"
Merge "Do not allow HEAD images/detail"