ovsdb-data: Add support for integer ranges in database commands

ovsdb-data: Add support for integer ranges in database commands

Adding / removing a range of integers to a column accepting a set of
integers requires enumarating all of the integers. This patch simplifies
it by introducing 'range' concept to the database commands. Two integers
separated by a hyphen represent an inclusive range.

The patch adds positive and negative tests for the new syntax.
The patch was tested by 'make check'. Covarage was tested by
'make check-lcov'.

Signed-off-by: Lukasz Rzasik <lukasz.rzasik@gmail.com>
Suggested-by: <my_ovs_discuss@yahoo.com>
Suggested-by: Ben Pfaff <blp@ovn.org>
Signed-off-by: Ben Pfaff <blp@ovn.org>