ONYX-71: Add log4j appender that logs in database

[ymarcon]

Jira issue originally created by user @plaflamme:

Add a log4j appender that sends its output to a database table so we can use SQL Select statements to find stuff inside.

Use JDBCAppender.

[ymarcon]

Comment created by dspathis:

Having looked into using JDBCAppender to implement this, I discovered the following:

• The log4j JDBCAppender class will likely be replaced in a future release (see the warning in the javadocs).
• The log4j 1.3 project, which does contain a replacement o this class (DbAppender), has been abandoned.
• The apache-log4j-receivers project, a backport of the log4j 1.3 functionality for log4j 1.2, contains DbAppender however it has not yet been released.
• Some alternative implementations do exist and have been made available to the public (see http://dankomannhaupt.de/projects/index.html), but their are of unknown quality (to me, at least).

Based on the above, I recommend holding off on this feature. When log4j 2.0 is released (?), we will have the necessary functionality to implement this.

[ymarcon]

Comment created by @obiba-ci:

Integrated in Magma #129 (See [http://hudson.obiba.org/hudson/job/Magma/129/]) :

• AbstractValueTableWrapper: Removed wrapped table instance variable in favour of an abstract getter method.
• Updated FilteredValueTable to reflect changes to base class (AbstractValueTableWrapper).
• Implemented ValueTableReference.