add 'early preview' tag to Metrics app on landing

- temporary code to detect metrics app and add a
tag to display 'early preview' for first iteration

- add early preview tag to metrics title
- tweaked the metrics growl messages to only
show when metrics view is active
Merge pull request #809 from strongloop/fix/85-early-preview-tag-metrics

add 'early preview' tag to Metrics app on landing