[BISERVER-9545] Support for JPivot plugin.  Retrieving default members uses a SchemaReader retrieved from the connection, which is not automatically wrapped in a Locus.  This can cause failures in some cases (e.g.
retrieving default members on a role restricted dimension).  Modified to use a Locus.
Merge pull request #683 from mkambol/biserver-9545

[BISERVER-9545] Support for JPivot plugin.  Retrieving default members u...