ospfd: json support for ospf database command.

ospfd: json support for ospf database command.

Description:
Added json support to ospf lsdb command and its subcommands.
Added json to the following sub commands.
show ip ospf  database json
show ip ospf  database router json
show ip ospf  database network json
show ip ospf  database external json
show ip ospf  database summary json
show ip ospf  database asbr-summary json
show ip ospf  database nssa-external json
show ip ospf  databas max-age json
show ip ospf  database self-originate json

Signed-off-by: Rajesh Girada <rgirada@vmware.com>