if prefix, only handle files that have the prefix

Fixes this situation:
```
GET /vendors/bootstrap-3.1.1/bootstrap.min.css 304 4ms
  source : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\vendors\jquery-2.1.1\jquery-2.1.1.
min.coffee
  read : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\vendors\jquery-2.1.1\jquery-2.1.1.mi
n.coffee
  source : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\js\col-square.coffee
  read : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\js\col-square.coffee
  source : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\js\row-extends-to-bottom.coffee
  read : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\js\row-extends-to-bottom.coffee
GET /vendors/jquery-2.1.1/jquery-2.1.1.min.js 304 30ms
  source : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\js\jade-runtime.coffee
  read : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\js\jade-runtime.coffee
GET /js/col-square.js 304 30ms
GET /js/row-extends-to-bottom.js 304 29ms
  source : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\app.coffee
  read : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\app.coffee
GET /js/jade-runtime.js 304 5ms
GET /css/style.css 200 85ms - 0b
  render : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\app.coffee
GET /coffee/app.js 200 15ms - 310b
GET /css/helpers.css 200 97ms - 657b
  source : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\templates\view-table.coffee
  read : D:\Users\Cole\Desktop\RareWire-dashboard\static\coffee\templates\view-table.coffee
GET /templates/view-table.js 200 19ms - 2.55kb
```

```jade

block footer
  script(src="/js/col-square.js")
  script(src="/js/row-extends-to-bottom.js")
  //- Declare template as object before loading jade templates
  script.
    var template = {}
  script(src="/js/jade-runtime.js")
  script(src="/templates/view-table.js")
  script(src="/coffee/app.js")
```