Fix issue #25

I fix issue #25 which prevents the login page from being displayed in
some production environments.  I fix it by excluding sensible properties
such as ``balance``, ``closingBalance``, or ``paymentStateColor`` from
being indexed.

Furthermore, I remove the Grails environment part from the path where
the searchable plugin stores the index.  And I locate the generated log
files in the production environment in the directory ``log`` under the
SpringCRM base data directory.