Remove silent option from Model#set.
Fixed to pass with edge version of Underscore

Due to changes in https://github.com/documentcloud/underscore/commit/0ab5bdccd41e55fb02331ec7d2d0053e0bdac9e3 need to fix Backbone.Model test. It would be helpful because some people may use Backbone's unit tests in their Backbone-related projects (plugins for example).
Update due to recomendations
Merge remote-tracking branch 'remotes/documentcloud-original/master'
Merge pull request #2282 from DreamTheater/patch-1

Fixed to pass with edge version of Underscore
Fix #2312 - Clarify eventsApi logic.
improve rendering of travis-ci build status

* destretch by removing dimensions, also future proofs size changes
* forcibly move to next line
* uses css attr selector, other strategies may be better
adding a class to the travis badge
Document master as the target branch for pull requests.
Reword based on discussion.
Merge pull request #2319 from braddunbar/target-branch

Document master as the target branch for pull requests.
Merge pull request #2113 from braddunbar/silent

Remove silent option from Model#set.
Correct minor spelling mistake.
Merge remote-tracking branch 'remotes/documentcloud-original/master'
Merge remote-tracking branch 'remotes/origin/master'