adding the default value for mail.server_type back.

if the user was using pop in 4.x, this defaults to 0.
a ton of code depends on it being 0, and not undefined.
alecf removed it, using it as a way to tell if we needed to migrate the prefs
or not.  Instead, I'm using other prefs to do that.
see nsMsgAccountManager::ProceedWithMigration() for the logic.

mailnews/mailnews.js

@@ -26,9 +26,9 @@ pref("news.wrap_long_lines",                false);
 pref("mail.inline_attachments",             true);
 
 // Mail server preferences, pop by default
-pref("mail.server_type",                    0); // 0 pop, 1 imap,
-						// (Unix only:)
-						// 2 movemail, 3 inbox          
+pref("mail.server_type",	0); 	// 0 pop, 1 imap,
+					// (Unix only:)
+					// 2 movemail, 3 inbox          
 pref("mail.auth_login", true);
 
 pref("mail.use_drafts", true);

modules/libpref/src/init/mailnews.js

@@ -26,9 +26,9 @@ pref("news.wrap_long_lines",                false);
 pref("mail.inline_attachments",             true);
 
 // Mail server preferences, pop by default
-pref("mail.server_type",                    0); // 0 pop, 1 imap,
-						// (Unix only:)
-						// 2 movemail, 3 inbox          
+pref("mail.server_type",	0); 	// 0 pop, 1 imap,
+					// (Unix only:)
+					// 2 movemail, 3 inbox          
 pref("mail.auth_login", true);
 
 pref("mail.use_drafts", true);