User sync performance

[calebwashburn]

This PR will address issue - #365

Timing samples from a cloud foundry deployment with 400 orgs, 5 spaces per org and 10 ldap users per space as space developer.

It took 117.426 seconds to update space users (latest dev build)
It took 501.163 seconds to update space users for v1.0.51
It took 2821.598 seconds to update space users v1.0.58

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this. Unfortunately, the Pivotal Tracker project is private so you may be unable to view the contents of the story.

The labels on this github issue will be updated when the story is started.