Longer deprecation message to identify fault

Recommend extending the deprecation backtrace to make it easy to find faults, as active_supports dependencies is pretty much all you get for 5 lines at the moment.

#### Example
```
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@phoenix/gems/guard-2.8.2/lib/guard/guard.rb:3:in `<top (required)>'
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@phoenix/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@phoenix/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `block in require'
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@phoenix/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@phoenix/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@phoenix/gems/guard-jasmine-1.17.0/lib/guard/jasmine.rb:4:in `<top (required)>'
	 >> /Users/dave/.rvm/gems/ruby-2.1.2@global/gems/bundler-1.6.2/lib/bundler/runtime.rb:85:in `require'
```
As you can see the stack trace at 5 lines in length is just not enough to expose the culprit.

Thanks