cleanup
aggregator doesnt have getFunctionID anymore, so I remved it
Merge branch 'master' into categorical_hazard_data
allow string as keys for categorized styles
merge
revert wrong commit
added no_data support
Merge branch 'categorical_hazard_data' of github.com:essc/inasafe into categorical_hazard_data

Conflicts:
	safe/impact_functions/styles.py