Upgrade the uglifier gem

Update UglifyJS to 2.4.14

https://trello.com/c/ENToaIyn
Upgrade the capybara gem

* 'asserttext', 'assertnotext', 'asserttitle', 'assertnotitle' methods
  added
* have_title matcher now supports :wait option
* More descriptive have_text error messages
* New modal API ('acceptalert', 'acceptconfirm', 'dismissconfirm',
  'acceptprompt', 'dismiss_prompt')
* Warning when attempting to set contents of a readonly element
* Suport for and/or compounding of Capybara's RSpec matchers for RSpec 3
* :filloptions option for 'fillin' method that propagates to 'set' to
  allow for driver specific modification of how fields are filled in
* Improved selector/filter description in failure messages
* HaveText error message now shows the text checked all the time
* RackTest driver no longer attempts to follow an anchor tag without an
  href attribute
* Warnings under RSpec 3
* Handle URI schemes like about: correctly
* RSpecs exposedslglobally option is now followed
* New window management API
* Speed improvement for visible text detection in RackTest. Thanks to
  Phillipe Creux for instigating this
* RSpec 3 compatability
* 'saveandopen_screenshot' functionality
* Server errors raised on visit and synchronize
* CSSHandlers now derives from BasicObject so globally included
  functions (concat, etc) shouldn't cause issues
* touched reset after session is reset

https://trello.com/c/tvQnXcMN