Fix loadbalance to add nodes when below min_nodes
Raise an exception if min_nodes > max_nodes in loadbalancer
Merge branch 'loadbalance_min_max_compare_exception' of github.com:datacratic/StarCluster into vanilla_improvements

Conflicts:
	starcluster/balancers/sge/__init__.py
Merge branch 'loadbalance_min_nodes_fix' of github.com:datacratic/StarCluster into vanilla_improvements