Log errors from tomcat

Sometimes the error from crowd seems to come from tomcat, in the form of standard
error pages of HTML. This makes a crude attempt at parsing such errors and logging
the actuall error.

This came up when we upgraded crowd internally and our new server was IPv6 aware. It
gave us some proxy IPs we hadn't whitelisted.
Merge pull request #1 from omega/log-errors

Log errors from tomcat