Ignore files generated by the findbugs report

Change-Id: Ie9aa5791ef6a565cb3e27af5c34eceac384b7b45
Reviewed-on: http://gerrit.dmdirc.com/223
Reviewed-by: Gregory Holmes <greboid@dmdirc.com>
Tested-by: Gregory Holmes <greboid@dmdirc.com>

.gitignore

@@ -23,3 +23,5 @@ __history
 *.a
 *.o
 *.ppu
+/reports/findbugs/
+/reports/report-fb.html