Do minor style fixes

modules/exploits/windows/mysql/mysql_start_up.rb

@@ -71,7 +71,7 @@ class Metasploit3 < Msf::Exploit::Remote
 
     begin
       res = mysql_query(q)
-      return rows if not res
+      return rows unless res
       res.each_hash do |row|
         rows << row
       end
@@ -79,7 +79,7 @@ class Metasploit3 < Msf::Exploit::Remote
       return rows
     end
 
-    return rows
+    rows
   end
 
   def is_windows?
@@ -90,7 +90,8 @@ class Metasploit3 < Msf::Exploit::Remote
   def get_drive_letter
     r = query("SELECT @@tmpdir;")
     drive = r[0]['@@tmpdir'].scan(/^(\w):/).flatten[0] || ''
-    return drive
+
+    drive
   end
 
   def upload_file(bin, dest)
@@ -108,14 +109,14 @@ class Metasploit3 < Msf::Exploit::Remote
       return
     end
 
-    if not is_windows?
+    unless is_windows?
       print_error("#{peer} - Remote host isn't Windows.")
       return
     end
 
     begin
       drive = get_drive_letter
-      return if not drive
+      return unless drive
     rescue RbMysql::ParseError
       print_error("Could not determine drive name")
       return