added clear_persistent_cache and minor update to persistent caching#440

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salmanulhaq wants to merge 2 commits intoboostorg:masterfrom salmanulhaq:persistent_cache

+47-13

Commits on Mar 21, 2015

added clear_persistent_cache and minor update to persistent caching
Salman Ul Haq
committed

Commits on Mar 22, 2015

clear_persistent_cache now static function and changed hash following @ddemidov suggestion
Salman Ul Haq
committed