BibDocFile: new document data model

* New document data model allowing for more flexible data storage.

* Allows to have standalone documents not attached to records.

* Allows to store "more info" dictionaries about documents in more
  flexible manner.

* Enables relation between documents and particular versions.

* Provides new BibUpload extensions (BDM, BDR) allowing to manipulate
  all important data structures.

* After installing this commit on an exiting database, the upgrade
  procedure is executed.  (Can be lengthy depending on the number
  of records.)

* Merge note: checked tabcreate and upgrade statements and modified them
  so that they would lead to exactly identical results.  Files touched:
    modules/miscutil/lib/upgrades/invenio_2012_11_15_bibdocfile_model.py
    modules/miscutil/sql/tabcreate.sql

Signed-off-by: Tibor Simko <tibor.simko@cern.ch>