Read preload ns from resources for fixing 0.5.15

The latest `lein-figwheel` `0.5.15` takes away a couple of functions that were used to build up the bootstrapping/connection scripts and namespaces.

The new version would need to come up with a way to read the scripts themselves using `io/resource`.

Start by locating the bootstrapping and connection scripts affected by lein-figwheel 0.5.15, then inspect how those scripts and namespaces are currently obtained. Use io/resource to read the scripts, and verify that live reload still works with lein-figwheel 0.5.15.

Written by the indexing model from the issue text.