API: create merge request

lib/api/merge_requests.rb

@@ -18,7 +18,17 @@ module Gitlab
 
       #create merge_request
       post ":id/merge_requests" do
+        attrs = attributes_for_keys [:source_branch, :target_branch, :assignee_id, :title]
+        project = current_user.projects.find(params[:id])
+        merge_request = project.merge_requests.new(attrs)
+        merge_request.author = current_user
         
+        if merge_request.save
+          merge_request.reload_code
+          present merge_request, with: Entities::MergeRequest
+        else
+          not_found!
+        end
       end
 
       #update merge_request