Sinatra apps without views: NoMethodError

[bashcoder]

If a Sinatra app doesn't have a views/ folder, the method detect_views() returns nil instead of an empty array, unlike the other detect_*() methods in sinatra.rb.

https://github.com/codesake/codesake-dawn/blob/master/lib/codesake/dawn/sinatra.rb#L119

This causes a NoMethodError on line 37, which expects a valid @views array.

gems/codesake-dawn-1.2.0/lib/codesake/dawn/sinatra.rb:37:in `detect_reflected_xss': undefined method `each' for nil:NilClass (NoMethodError)

The simplest solution that doesn't require adding conditionals (or complicating existing ones) is simply to add a default empty array to the end of detect_views() on line 120.

[bashcoder]

This PR is a simpler approach to what was proposed in #95, and makes the interface consistent across all of the detect_*() methods.