Implemented back-end methods for pagination and sorting

MIFOSX-322, MIFOSX-323
Fixed the clientmapper issue
fixed the search centers and search groups issue,
'group level was not appended when the sqlQueryCrieteria is not empty
wip:added separate commands for associating/disassociating a client to group
Merge remote-tracking branch 'soc_anuruddha/mifosx-322,323'
Merge remote-tracking branch 'ashok/MIFOSX-334'
Merge remote-tracking branch 'soc_anuruddha/mifosx-326'