It introduces the 'FilterProvider' property in the media descriptor
to optionally bypass the normal loading process and let the external
filter provider to handle the loading.

For now I'm overwriting the csv import filter just to see how this
could work just as an experiment.

Orcus still needs a lot of work, and it crashes very often at the
moment.

Change-Id: I11b34572c71073144804a7d0dd5176c8067d8deb