The statistics module should provide the following functionality:

• ability to build histograms and statistics against mongodb collections,
• an "analyze" command that triggers the statistics collection process,
• a way to access a cache object that knows how to retrieve statistics from disk, and provides access to collection histograms keyed by paths.

Based on this functionality this task:

• CE should be extended to request histograms for certain collections and paths, and use them when available.
• Implement basic integration (JS) tests that test CE accuracy against data stored in a collection.
  • Statistics is built via an "analyze" command.
  • The JS tests use the golden-test framework implemented by SERVER-67415.