Add a /network/http route

[postmodern]

Add a route and form for submitting arbitrary HTTP requests and displaying the responses. It should use JavaScript to send a asynchronous request to another backend route (ex: /network/http/request), waiting for a response, then parsing and rendering the JSON response that represents the Net::HTTPResponse that is returned as pretty HTML.

There should also be an Import checkbox which would cause the request and response to automatically be added to the database as Ronin::DB::HTTPRequest and Ronin::DB::HTTPResponse records.

[postmodern]

Implemented by PR #115.