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

![screenshot](https://cloud.githubusercontent.com/assets/1140553/5436177/803945ce-8463-11e4-88b0-ed16976a9547.png)

![screenshot 1](https://cloud.githubusercontent.com/assets/1140553/5436176/8038f948-8463-11e4-820f-ab4a4e608f47.png)

/to: @bajtos 
/cc: @anthonyettinger