Add oslo.utils requirement

With the release of oslo.utils, keystoneclient can make use of it
rather than using the functions in oslo-utils.

Change-Id: I1b5392f10f8b67c9c3ac3bc3d2dd06ea08417aa6
Use oslo.utils

keystoneclient was using utility function from oslo-incubator
rather than oslo.utils.

Change-Id: I2909a2150b9556e54ef88e72358fda1cf8b7cc1c
Merge "Add oslo.utils requirement"
Merge "Use oslo.utils"
Revert "Use oslo.utils"

This reverts commit 68c2fad55a71ca511ff959e589aa0a3f3dbd4b78.

Looks like this broke the stable branches. :(

Change-Id: I9d190e211ecfa80d573a6c48c0b485f3506fe947
Closes-Bug: #1357652
Revert "Add oslo.utils requirement"

This reverts commit 64a21b56f5f44813f51697190baa560d593ba28c.

The dependency is being reverted since it broke the stable branches,
so removing this as well.

Change-Id: Iafe7831b53a30c14cb4b70c3d9b669d70266c8f6
Partial-Bug: #1357652