Implemented Emailing

Replyto email is now set (if configured)
If you reply to the email address it is sent from a autoreply will be sent saying you did so.
Email will be sent if
    An assignment has passed its due date and that person has not submitted the assignment yet
    A grade is changed/written
    Email Address is entered into the system (confirmation email)
    An assignment is created
    An assignment name, number, duedate or description is modified

When refreshing filebrowser it will no longer say no files found and will no longer have colors or tooltips
Date now defaults to current time when overlay is opened
Fixed showing blank tooltip in filebrowser
Right clicking on the top left in gradebook will now always allow you to add a name or assignment
Fixed startup saying no files found when downloading files
Added loading spinner to intial load of filebrowser
Fixed rename/redownload
Fixed date saving hour wrongly in certain situations
Fixed allowing bulk actions while refreshing
Fixed not changing date graded when overwriting grade unit testing
Fixed not being able to remove email
Fixed being way to relaxed when searching for names in gradebook, now it only ignores case
Fixed not being able to close overlays when nothing was entered
Fixed an issue showing points when viewing an assignment
Fixed modifying date resetting to current time
Fixed potential NPE grading (which has been around for quite a while interestingly enough)