add testFeedExists script; remove redundant uniqueId functions; add CFBundleURLTypes info.plist key

EvergreenTests/ScriptingTests/scripts/testFeedExists.applescript

@@ -0,0 +1,10 @@
+-- this script just tests that no error was generated from the script
+try
+	tell application "Evergreen"
+		 exists feed 1 of account 1
+	end tell
+on error message
+	return {test_result:false, script_result:message}
+end try
+
+return {test_result:true}