Remove py3kcompat module

Update common apiclient from Oslo for that. I've updated
to oslo-incubator of commit 04a1abe59ac39890f57d2eed57d3d1b12bb5d757

List of changes:

  04a1abe Revert "Removed set_loaded() method from Resource class"
  86707cd Remove None for dict.get()
  6650435 Fix usage of dict.keys in apiclient.exceptions
  35dc1d7 py3kcompat: remove

Change-Id: I4334c941531e12faabcf023a836c6ad850b3b4cc
Merge "Remove py3kcompat module"