Improve Dropdown Menu in Files View

* Prevent overflow
* Set z-index to ensure display on top of tab with spinner
* Make animation more subtle
* Increase padding
Ensure Pictograms of new File Stages also Blink

Before the icon was only animated for a known set of stages.
Merge pull request #207 from tf/files-dropdown-fixes

Improve Dropdown Menu in Files View
Merge pull request #208 from tf/file-thumbnail-blink

Ensure Pictograms of new File Stages also Blink