Rename apps.json files throughout project

- Remove `appveyor.yml`
- Add project description to CMakeLists.txt
- Add project homepage url to CMakeLists.txt

assets/linux-deb/preinst

@@ -4,6 +4,6 @@ if [ -f /etc/sunshine/sunshine.conf ]; then
         cp /etc/sunshine/sunshine.conf /etc/sunshine/sunshine.conf.old
 fi
 
-if [ -f /etc/sunshine/apps_linux.json ]; then
-        cp /etc/sunshine/apps_linux.json /etc/sunshine/apps_linux.json.old
+if [ -f /etc/sunshine/apps.json ]; then
+        cp /etc/sunshine/apps.json /etc/sunshine/apps.json.old
 fi