Added total_state_entries metric
Added tests for total_state_entries
Merge branch 'feature/issue-3-total-sessions-metric' into feature/issue-4-state-total-metric

Conflicts:
	test/test_metrics_helper.js
Added total_state_exits metric
Added tests for total_state_exits metric
Merge branch 'develop' into feature/issue-4-state-total-metric

Conflicts:
	test/test_metrics_helper.js
Changed to inc aggregation method
Changed method to act on any state event
Changed tests to match changes to function
Fixed docstring
Docstring fix
Changed to throw an input in case of bad state action rather than defaulting to enter
Merge branch 'feature/issue-4-state-total-metric' into develop