Fix bug with cft command

Previously, if there was 1 friend with no common free time,
cft command would only display an error saying that user and friend
have no common free times, and not proceed to show the friends that
have common free times.

This issue has been fixed. Expected output should now be:
You and Friend have no common free time!
You and John Doe have common free times at:
...

src/main/java/seedu/address/logic/commands/CommonFreetimeCommand.java

@@ -92,7 +92,7 @@ public CommandResult execute(Model model) throws CommandException {
      * @return a message indicating that the user and the given friend have no common free time
      */
     public static String createNoOverlapFriendMessage(Person friend) {
-        return "You and " + friend.getName().toString() + " have no common free time!";
+        return "You and " + friend.getName().toString() + " have no common free time!\n";
     }
 
     /**
@@ -129,7 +129,7 @@ public StringBuilder createCommonFreeTimeMessage(Person user, Person friend) thr
         Schedule friendSchedule = friend.getSchedule();
         List<FreeTime> commonFreeTimeWithFriend = userSchedule.getThisWeeksFreeTimesWith(friendSchedule);
         if (commonFreeTimeWithFriend.isEmpty()) {
-            throw new CommandException(createNoOverlapFriendMessage(friend));
+            return new StringBuilder(createNoOverlapFriendMessage(friend));
         } else {
             StringBuilder sb = new StringBuilder("You have common free times with "
                 + friend.getName().toString()

src/main/java/seedu/address/logic/parser/AddScheduleCommandParser.java

@@ -56,7 +56,7 @@ public AddScheduleCommand parse(String args) throws ParseException {
         String indexString;
 
         String eventName = argMultimap.getValue(PREFIX_EVENTNAME).get().toUpperCase();
-        String eventType = argMultimap.getValue(PREFIX_EVENTTYPE).get().toUpperCase();
+        String eventType = argMultimap.getValue(PREFIX_EVENTTYPE).get().toLowerCase();
         String schedule = argMultimap.getValue(PREFIX_SCHEDULE).get();
 
         try {

src/main/java/seedu/address/logic/parser/RemoveScheduleCommandParser.java

@@ -47,7 +47,7 @@ public RemoveScheduleCommand parse(String args) throws ParseException {
         try {
             String indexString = argMultimap.getPreamble().toLowerCase();
             String eventName = argMultimap.getValue(PREFIX_EVENTNAME).get().toUpperCase();
-            String eventType = argMultimap.getValue(PREFIX_EVENTTYPE).get().toUpperCase();
+            String eventType = argMultimap.getValue(PREFIX_EVENTTYPE).get().toLowerCase();
             if (indexString.equals("user")) {
                 return new RemoveScheduleCommand(eventName, eventType, null);
             } else if (Integer.parseInt(indexString) > 0) {