Made amendments based on review

Fixed 'prepend' terminology in comments, restored old loop as it seems to work for me now in overwriting the file as one overall multiline instead of overwriting the file with each line at a time, code simplification based on review comments... credits-adding will come in the next commit.

src/modules/displaymanager/main.py

@@ -495,26 +495,21 @@ class DMlightdm(DisplayManager):
                 text = lightdm_conf.readlines()
                 # Check to make sure [SeatDefaults] or [Seat:*] is in the config,
                 # otherwise we'll risk malforming the config
-                if not '[SeatDefaults]' in text and not '[Seat:*]' in text:
-                    addseat = True
+                addseat = '[SeatDefaults]' not in text and '[Seat:*]' not in text
 
             with open(lightdm_conf_path, 'w') as lightdm_conf:
                 if addseat:
-                    # Append Seat line to start of file rather than leaving it without one
+                    # Prepend Seat line to start of file rather than leaving it without one
                     # This keeps the config from being malformed for LightDM
                     text = ["[Seat:*]\n"] + text
-                loopcount = 0
                 for line in text:
                     if 'autologin-user=' in line:
                         if do_autologin:
                             line = "autologin-user={!s}\n".format(username)
                         else:
                             line = "#autologin-user=\n"
-                        text[loopcount] = line
-                    loopcount += 1
 
-                lightdm_conf.write("".join(text))
-                loopcount = 0
+                    lightdm_conf.write(line)
         else:
             try:
                 # Create a new lightdm.conf file; this is documented to be