Implemented DELETE and GET /mac_address_ranges/<uuid>

* Added exceptions.MacAddressRangeNotFound,
  exceptions.MacAddressRangeInUse
* Implemented tests for plugin.get_mac_address_range
* Implemented tests for plugin.delete_mac_address_range
added wiki submodule
Merge pull request #95 from jkoelker/wiki

added wiki submodule
Merge pull request #84 from asadoughi/delete_mac_address_range

Implemented DELETE and GET /mac_address_ranges/<uuid>
Optimized switch cloning

Implements switch spanning for the optimized driver and adds a couple
columns to the nvp lswitch table for the clone details lookup.