Fix OAUTH docs to remove duplicate 400

The OAUTH docs had the 400 Bad Request status listed multiple times.

Change-Id: I50fd28edb45e41b14411547251bcc00c011376e4
Delete unused directory

The files in api-ref/src/wadls/image-api/src/v2.0 are unused, remove
them. We use ../v2 instead.

Change-Id: If9cca5944f9801244c8c24abc465c4131d8a4774
Merge "Delete unused directory"
Merge "Fix OAUTH docs to remove duplicate 400"