Minor improvements to file upload.

Updated file upload so that the icon of the new upload item reflects if it is a file or notebook, added the ability to use the "Enter" key in the filename text box to cause the upload to happen, and make it so that the list of files refreshes immediately upon successful upload.

Possible other simple enhancements: use ESC key from textbox to cancel upload, add a subdirectory-create button. I understand that a redesign may be coming to the whole dashboard, but these are all small and remove annoyances.