Bug 12412: Add ability for plugins to convert arbitrary files to MARC from record...

Bug 12412: Add ability for plugins to convert arbitrary files to MARC from record staging tool

Many libraries would like to be able to import various types of files as
MARC records ( citations, csv files, etc ). We can add a new function to
the plugins system to allow that kind of behavior at a very custom
level.

Test Plan:
1) Ensure you have plugins enabled and configured correctly
2) Installed the attached version 2.00 of the Kitchen Sink plugin
3) Download the attached text file
4) Browse to "Stage MARC records for import"
5) Select the downloaded text file for staging
6) After uploading, you should see a new area "Transform file to MARC:",
   select "Example Kitchen-Sink Plugin" from the pulldown menu
7) Click 'Stage for import"
8) Click 'Manage staged records"
9) You should now see two new MARC records!

Signed-off-by: Aleisha <aleishaamohia@hotmail.com>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described - interesting new feature.
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>