Add server maintenance mode.

Maintenance mode prevents a server from having new connections made
to it and stops MaxScale from monitoring a server. It is designed
to allow a server to be taken out of an active cluster for maintenance.
It prevents new connections and allowsg existing connections to
drain away prior to performaing maintenance on the server.
Fix compilation error
Bug #443, http://bugs.skysql.com/show_bug.cgi?id=443
monitors used mysql_ping without MYSQL_OPT_READ_TIMEOUT which caused read to block. Fixed in mysql and galera monitor.
Added log writing per each status change of each server and repeatedly if server is not running.

Removed SERVER_IS_JOINED checks from rwsplit router.
Merge pull request #5 from skysql/MAX-122

Max 122
monitor_interval added

monitor_interval added
fixed macro name

fixed macro name
Removed references to SERVER_IS_JOINED status from readwritesplit.c because rwsplit for Galera doesn't use that status at all.
Addition of the module utilities functions
Merge branch 'develop' into MAX-65
A filter parameter fix and a new filter, the regex filter.

The regexfilter is an example of a query rewriting filter that uses
regular expressions to match the SQL text and allows a replacement text
to be used for each match of the regular expression.

Regexfilter has no special SQL undertanding, it merely uses the features
avialable inthe regex library to perform matches.

Statements that span multiple packets are not supported by the regex
filter.
Fixed for typo in modutil.h

Addition of timestamps to the query log produced by the QLA filter