[PITR] REST API validation issues

The endpoint allows max history and granularity to be updated when pitrEnabled is false

[root@node1-cb700-beta-centos7 ~]# curl -X POST http://localhost:8091/pools/default/buckets/test-bucket -u Administrator:password -d pitrEnabled=false -d pitrMaxHistoryAge=86400

Also, it is allowing pitrMaxHistoryAge to be set less than pitrGranularity

[root@node1-cb700-beta-centos7 ~]# curl -X POST http://localhost:8091/pools/default/buckets/test-bucket -u Administrator:password -d pitrEnabled=true -d pitrMaxHistoryAge=17000 -d pitrGranularity=17500

Please feel free to ignore if this is acceptable behavior