Now that we are python3 only, we should move to using the built
in version of mock that supports all of our testing needs and
remove the dependency on the "mock" package.
This patch moves all references to "import mock" to
"from unittest import mock". It also cleans up some new line
This patch is the inital move of the provider driver modules from
Octavia to octavia-lib.
This patch also moves the required constants and makes them available
to the provider drivers.