Add vty command to show summary of all or filtered subscribers

Adds the following commands:

show subscribers all - Display summary of all entries in HLR
show subscribers (imsi|msisdn|cs|ps) ... As above but filter on search field/string
show subscribers last seen - Display only subscribers with data in
Last LU update field, and sorts by Last LU.

Change-Id: I7f0573381a6d0d13841ac6d42d50f0e8389decf4
5 files changed