Added totalSessions metric
Added tests for totalSessions metric
Fixed tests for node.js 0.10
Merge branch 'feature/issue-2-new-user-metric' into feature/issue-3-total-sessions-metric

Conflicts:
	test/test_metrics_helper.js
Merge branch 'feature/issue-2-new-user-metric' into feature/issue-3-total-sessions-metric
Merge branch 'develop' into feature/issue-3-total-sessions-metric
Added default new session metric label
Split out the metrics init test code into the appropriate describe block
Changed total_sessions metric to use the inc aggregation methods
changed total_unique_users to use inc metric
Merge branch 'feature/issue-3-total-sessions-metric' into develop