versions API: ignore request with a body

Update the OS API versions controller so it ignores requests
with a body. Previously an incoming (unauthenticated)
request to the versions API would log a TypeError trace
in the nova-api.log file with the following message:

TypeError: index() got an unexpected keyword argument 'body'

Change-Id: Icc3ccfc537b13627b8d5ba43ae3ba91e34e08c9e
Closes-bug: #1306727
Merge "versions API: ignore request with a body"