Fix to #547, http://bugs.skysql.com/show_bug.cgi?id=547
readwritesplit.c:get_dcb now searches for master if slave is not available
Completion to fix for http://bugs.skysql.com/show_bug.cgi?id=547
server.h:added macro SERVER_IS_ROOT_MASTER for finding valid candidate for root master
readwritesplit.c: wrote open three if conditions in get_root_master_bref for clarity
Merge remote-tracking branch 'origin/release-1.0beta-refresh' into cmake_build