Added symlink/dereference and modified lvm auto guess options

The following options are added/modified:
- --dereference-symlink {'none', 'soft', 'hard', 'all'}:
    Follow Hard and soft links and archive and dump the files
    they refer to according the choise option set.
- --lvm-auto-snap: now takes as argument the path you want to
  guess for the lvm group and volume name

Also few types where removed. Dependencies are also update,
as now pymongo and mysqldb module needs to be installed

Change-Id: I99b780ff7b34dd85162634855357e1785db0e893