Initial working metrics impl - no tests

This fetches tenants and groups from CASS and servers from nova for all
these tenants and gives out total desired and total actual for a region
handling groups with 0 servers too

also minor code improvements
reactor as optional arg
Merge branch 'master' into metrics
moved get_scaling_group_servers to convergence.py
Started convergence tests

Modified method to take treq impl
minor clarity in code
Merge branch 'master' into metrics
StubTreq2 - an easier API with more functionality
get_all_server_details tests implemented
get_scaling_group_servers filtering change - thanks @cyli

removing status based filtering out of get_scaling_group_servers and added its tests
Merge branch 'master' into metrics

Conflicts:
	otter/convergence.py
	otter/test/test_convergence.py
Moved metrics.py in otter/

Also added tests for get_scaling_groups
metrics collection tests added

Split getting all metrics in separate function
Merge branch 'master' into metrics

Conflicts:
	otter/convergence.py
stdout print is optional

This way tests will not print on screen
shorter statement
get_scaling_groups returns list

instead of always grouping them based on tenant.
Also added function to print customers with Rackconnect setup
Remove tryfer and yunomi reqs until we need them, remove duplicate req in dev-requirements.txt
added function to check different configs