Rails 5 compatibility

[ekampp]

This is more a request for comments and a general discussion than an actual pull-request.

This is the patch that I'm using for Rails 5 compatability, but there might be better ways. So let's explore.

Rails 5 has changed method signature for ActionDispatch::FileHandler to take a hash of headers and not a single string.

module ActionDispatch
  class FileHandler
    def initialize(root, index: 'index', headers: {})
      # ... 
    end
end

[romanbsd]

Hi! First of all, thanks for your PR.
I think that what's missing is to add a Rails version check here, and either provide the second parameter as string (for Rails::VERSION::MAJOR < 5) or as {headers: ...} for >= 5.

[ekampp]

Added a Rails' major version check, and reimplemented backwards compatability.

[romanbsd]

Thanks!