user expects to attach/update screenshot to a requirement using InkFile

* using filepicker in proof forms
* extract proof form partial for new/edit views
* adding page header for new/edit views
* don't break Demeter's Law
* partial fix for specs, pending specs for new/edit
* display current proof image in edit page
* title for current image, moving out form container
* apply twitter bootstrap to proof form buttons
* preview attached image in new proof form
* extracting current proof image in a partial
* fix current image proof for edit proof form
* restrict services for filepicker to computer only
* adding httparty
* removing old image file when updating proof