Add (descriptive) label to permission resource and database schema

Add (descriptive) label to permission resource and database schema to avoid having to hardcode a descriptive name for a permission. For example:

This descriptive label can be used in user interfaces so that a descriptive (or friendly) name does not have to be hardcoded.

GET api/v1/permissions/1

200 OK
{
  "href" : "http://your.ambari.server/api/v1/permissions/1",
  "PermissionInfo" : {
    "permission_id" : 1,
    "permission_name" : "AMBARI.ADMIN",
    "permission_label" : "Administrator",
    "resource_name" : "AMBARI"
  }
}