* Replaced cancel/delete button in files area
* Consolidated Image upload styles with AssetUpload styles
* Changed name of step 2 in image upload
* Made image editing hidden by default, so multiple files can be seen,
and added ability top open and close
* Tweaked styles in on page upload field (status colour and file name
width)
1. Refactored some gridfield styles to enable reuse (created a mixin
file to hold mixins that generate specific css objects/elements).
2. Made some scss comments use // so they wouldn't appear in generated
css
