Refactoring of Benchmark Context Cleanup

The following blueprint will contain a series of patches that will address the following: Refactoring of benchmarks/utils.py to improve cohesion. Splitting user and admin cleanup to their respective classes, re-structure context/utils.py to be more OO.

In detail, the following changes will represent the series of changes it will be deliver:

First Patch:
1) Add a cleanup directory to context,
2) Rename 'cleaner' to 'cleanup' and move it to the directory mentioned above,
3) Split and move everything related to cleanup under benchmark/utils.py and move it to cleanup/utils.py
4) Add and fix unit tests accordingly

Another patch:
1) Split 'user' and 'admin' cleanup to 2 separate classes
2) Add, and update, unit tests

Two or more patches:
1) Refactor context/utils.py to use a more OO approach, by abstracting the common functionality to a base class named Cleaner, and with a method init that takes context['users'], and abstract method that doesn't take any args, but actually executes the cleanup code.
2) Then make all service cleanups extend and implement the Cleaner base class.
3) Add unit tests

Final patch:
1) Adding a retry mechanism for cleanups
2) Improve performance of the cleanup process
3) Add unit tests for this functionality