9f8a8341f7
Stevedore is the common approach to load plugins in OpenStack. It provides extremely much more options than current handmade plugins loader. We'll need it espessially for implementing pluggable resources provisioning code. In addition, setting vanilla and hdp as default plugins to make minimal config easier. Implements blueprint use-stevedore Change-Id: I96700bf34417c9bcd24d4f60b2deaa88a8c7c2d9