Preparation for flatpack support (#255)

- Updates to project and desktop metadata in preparation for flatpak packaging
- These updates are independent of flatpack
- This commit unmingles the actual flatpack packaging from #255

CMakeLists.txt

@@ -17,6 +17,7 @@ set (CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake/Modules/"
 set (ORGANIZATION_NAME "glabels.org")
 set (ORGANIZATION_DOMAIN "glabels.org")
 set (APPLICATION_NAME "glabels-qt")
+set (DESKTOP_FILE_NAME "org.glabels.glabels-qt")
 
 set (WEBSITE  "glabels.org")
 set (BUG_WEBSITE  "https://github.com/j-evins/glabels-qt/issues")