1. A system for supporting service level quorum in a data grid cluster, comprising: a plurality of computer servers, the data grid cluster executing thereon and the data grid cluster including a plurality of interoperating cluster nodes in the data grid cluster, wherein the data grid cluster supports performing a plurality of services including a root cluster service performed by all of the plurality of cluster nodes, a first service performed by a first subset of said plurality of cluster nodes, and a second service performed by a second subset of said plurality of cluster nodes, wherein the first service provides a different type of service than the root cluster service, and wherein the second service provides a different type of service than the root cluster service and the first service; a root cluster service quorum policy defined in a cache configuration file associated with the data grid cluster, wherein the root cluster service quorum policy specifies a minimum number of qualified root cluster service members that are required for performing root cluster service actions of said root cluster service; a first service quorum policy defined in the cache configuration file associated with the data grid cluster, wherein the first service quorum policy specifies a minimum number of qualified first service members required for performing first service actions of said first service; a second service quorum policy defined in the cache configuration file associated with the data grid cluster, wherein the second service quorum policy specifies a minimum number of qualified second service members required for performing second service actions of said second service; wherein the data grid cluster uses the root cluster quorum policy to determine whether root cluster service actions are allowed to be performed based on how many cluster nodes are operational in the data grid cluster; wherein the data grid cluster uses the first service quorum policy to determine whether first service actions are allowed to be performed based on how many cluster nodes are operational in said first subset of said plurality of cluster nodes; wherein the data grid cluster uses the second service quorum policy to determine whether second service actions are allowed to be performed based on how many cluster nodes are operational in said second subset of said plurality of cluster nodes; and wherein the first service is a partitioned cache service and the second service is a proxy service.