Fixed lightscreen building, runs, added desktop launcher.
Summary: Inclusion of lightscreen to solus
Test Plan: Works, however desktop file will need to be modified to work. Otherwise it launches from terminal and tray icon does load properly. Will update later with more fixes
Reviewers: Triage Team, JoshStrobl
Reviewed By: Triage Team, JoshStrobl
Subscribers: DataDrake, JoshStrobl
Differential Revision: https://dev.getsol.us/D2278