Do not shadow helpers with same method but more params

[mdelaossa]

When two helper methods are the same, but have different arguments (for example: api_v1_cats_owners_path(id: 1) vs api_v1_cats_owners_path(id: 1, owner_id: 2)) if the helper method with the least number of arguments is defined first (because the route was defined first) then it will shadow the longer route.

Example:
Consider the following routes:

      resource :cats do
        get '/' do
          %w(cats cats cats)
        end

        route_param :id do
          get do
            'cat'
          end
        end

        get ':id/owners' do
          %w(owner1 owner2)
        end

        get ':id/owners/:owner_id' do
          'owner'
        end
      end

The helper methods return:

api_v1_cats_owners_path(id: 1) #=> '/api/v1/cats/1/owners.json'
api_v1_cats_owners_path(id: 1, owner_id: 2) #=> '/api/v1/cats/1/owners.json'

which is wrong. api_v1_cats_owners_path(id: 1, owner_id: 2) should return '/api/v1/cats/1/owners/2.json'

This PR fixes this issue in the simplest possible way: when GrapeRouteHelpers::AllRoutes is generating @decorated_routes, it sorts the routes in descending order by the count of dynamic_path_segments it has.

Fixes #22

[mdelaossa]

BTW your travis build is failing on jruby-19 due to

Gem::Exception: can't find executable rake for gem rake. rake is not currently included in the bundle, perhaps you meant to add it to your Gemfile?