Stacktraces without `inProject`

Following up on https://github.com/bugsnag/bugsnag-notification-plugins/pull/78

New handlebars iterator: `eachSummaryFrame` which accepts a stacktrace, and will either display all the `inProject` lines, or displays the first 3 lines (if the language does not provide an `inProject` status).

Also, hidden within this, is a much richer view for Trello...

**Before**
![Screenshot Before](http://cl.ly/image/2T1R2Z2n3O12/Image%202014-07-18%20at%207.06.39%20am.png)

**After**
![Screenshot After](http://cl.ly/image/1x2a213c3y2S/Image%202014-07-18%20at%207.04.40%20am.png)

I have tested the Trello integration, obviously. But I'll also run a few random tests on a few of the other integrations to make sure they're working fine still.