Resolving URLs from contract (#1964)

* Fetching dapp from github.

* Unpacking dapp

* Removing hardcodes

* Proper Host validation

* Randomizing paths

* Splitting into files

* Serving donwloaded apps from different path

* Extracting URLHint to separate module

* Whitespace and docs

* Resolving from URLHint contract

* Fixing test

* Resolving githubhint url from registrar

* Proper redirections

* Fixing test

* fixing ethstore [ci skip]

* Correct version of registrar

* Removing superfluous Box