When screen sharing, add option for [Always Allow] #156
Description
Problem
Using remote access programs to access the secure desktop, there is an option missing to always allow a connection or program. This prevents unattended access to the GUI.
Ref: https://www.reddit.com/r/elementaryos/comments/1opaafh/how_to_do_unattended_remote_access_now_with/
Proposal
Add a checkbox to the screen select dialog to remember the decision, instead of having to interactively ask every time
Prior Art (Optional)
