Thijs Cadier b12196a41e Support for tailing queries
Add a tail convenience method that returns a tailing cursor
that implements the recommended way of tailing and reconnecting
in it's iterator implementation.

Also move optional arguments to separate type that can optionally be
added to the various methods.
..
bsonc.rs Initial version
client.rs Fix warnings and don't use scoped anymore
collection.rs Support for tailing queries
cursor.rs Support for tailing queries
database.rs Fix warnings and don't use scoped anymore
error.rs Initial version
flags.rs Support for tailing queries
lib.rs Fix warnings and don't use scoped anymore
read_prefs.rs Initial version
uri.rs Initial version
write_concern.rs Initial version