Cleanup
Fix to bug #510, http://bugs.skysql.com/show_bug.cgi?id=510, made every MaxScale thread to call mysql_thread_init() before entering poll_waitevents. Also main thread does this before starting services. Removed all calls to mysql_thread_init() and to mysql_thread_end() from elsewhere than from poll.c:poll_waitevents and from gateway.c:main

skygw_utils.cc: replace_literal: fixed memory leak
Merge branch 'MAX-237' into Z3