IoSessionInitiator sometimes tries to log null messages in case of IOExceptions

If there's an IOException in IoSessionInitator that's actually a java.net.ConnectionException, sometimes QFJ gets in a situation when it's trying to log an exception with NULL message.
If you have JDBC log configured you end up having with JDBC errors since the log tables aren't nullable.

This usually happens when you pull a network plug out from the server, and the intiator can't connect to it.

Stack trace:
com.mysql.jdbc.exceptions.MySQLIntegrityConstraintViolationException: Column 'text' cannot be null
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:931)
<snip>
at quickfix.JdbcLog.insert(JdbcLog.java:90)
at quickfix.JdbcLog.onEvent(JdbcLog.java:52)
at quickfix.CompositeLog.onEvent(CompositeLog.java:79)
at quickfix.mina.initiator.IoSessionInitiator$ConnectTask.connect(IoSessionInitiator.java:136)