Revert "Force pip version to 7.1.2 in tox for py32 (support dropped for latter versions)"
Revert "Force pip version to 7.1.2 in tox for py32 (support dropped for latter versions)"

This reverts commit 7b7165f5d8ab9cc29c29a02fbdd547113edb30b9.

MakerReduxCorp/mongoengine,Davidrjx/mongoengine,MongoEngine/mongoengine,sourcelair/mongoengine,larsbutler/mongoengine,cogniteev/mongoengine,cogniteev/mongoengine,ProgressivePlanning/mongoengine,Davidrjx/mongoengine,ConsumerPhysics/mongoengine,MakerReduxCorp/mongoengine,touilleMan/mongoengine