Fix Build

Summary:
* Fix private API incompatability with durabledict
* Move linting out of test task.
* Fix bug with handling comparison in decimals in 2.6. See quote below.

> Changed in version 2.7: A comparison between a float instance x and a Decimal instance y now returns a result based on the values of x and y. In earlier versions x < y returned the same (arbitrary) result for any Decimal instance x and any float instance y.

Test Plan: refactor so covered

Reviewers: NorthIsUp, kalail

Reviewed By: kalail

Differential Revision: http://phabricator.local.disqus.net/D12542