Some review / feedback changes - primarily related to Hosts and Racks. Add Unit Test file - still in progress.
Addressed review comments: 1-Clearing Blacklist everytime. 2-Fixed Requests Map building using AllocationSpecification. 3-private fields in Hosts, Racks, Allocation Specification. 4-Intersection set operation in Placement Policy Manager. 5-Using completed container count too while checking for Provisioning timeout.