Revert "Removes dirty checking from *Manager classes"

This reverts commit 70ba8ca6572c6fa7e574c08f0b597d3e490d137e.

Only reverts portions relevant to dirty checking.  Changes to coverage.py and test_coverage_basics left intact.
Changes to utils.hash_any over internal ._dohash()

Switches to utility function - identical to ._dohash
Merge pull request #18 from blazetopher/fixes_cpu

Fixes cpu usage