Use HTML5 Boilerplate

- Add some files from HTML5 Boilerplate
- Adopt the HTML5 Boilerplate layout
Use an anchor to invoke addPool()

- Replace the label with an anchor
- Move the ng-click from the th to the anchor
- Remove the CSS associated with th#addPool
Add a hint about the drag-n-drop feature

- Add a paragraph explaining the drag-n-drop feature
- Add a "prePopulated" variable that controls its visibility
- Set the prePopulated variable in reader.onloadend()
Add gpu-threads to the view

- Add gpu-threads text input to index.html
Add a GPUs slider

- Add an input range (1-4) for 'gpus'
- Add gpusChanged() that expands the values of each
  text field to reflect the selected number of gpus
- Add some CSS to style the input element
Make the filename settable in the UI

- Add a text input for the file name,
- default it to 'cgminer.conf' and,
- use it to set the anchor's download attribute
Use angular JSON methods

- Use angular.toJson instead of JSON.stringify
- Use angular.fromJson instead of JSON.parse
Improve the config file import logic

- Move the drag-n-drop support into a configFileHandler function
- Add a perGPUSettings array and use it