Remove skips for fixed bugs.

This commit removes skips from tests for bugs that have been fixed.
This currently unskips:

 - volume.admin.test_volume_types_extra_specs_negative:test_update_no_body
 - compute.images.test_images_oneserver:test_create_image_specify_name_over_256_chars

Also, the volume_types_client was updated to enable test_update_no_body
running. The extra_specs update method previously couldn't handle the
blank input from the negative test.

Change-Id: If13125bf5c0635b6190f1385e88d234db7a4156e
Fix test_flavor_extra_specs

This commit makes a number of changes to test_flavors_extra_specs
that cleans up a few of the tests in the file. Firstly, the
test_flavor_non_admin_set_get_unset_keys is split up into 3
separate tests. The original method, besides not working, was
testing 3 different permission cases. Secondly, an unused import
was removed. Thirdly, attrs were added for the negative tests in
the file. Lastly, all the try except blocks for the negative
tests were removed.

Change-Id: I4beba91918fc795628f2668b196a3bb150a610d8
Merge "Remove skips for fixed bugs."
Merge "Fix test_flavor_extra_specs"