Invoke the DocumentType listeners *before* the mappers are updated. This fixes an issue where if two or more concurrent percolate index requests are processed, the first request would the `.percolator` type mapping, but the real time percolator listener wouldn't be active, this would result in that the subsequent concurrent requests wouldn't be parsed and kept in memory and would never be included in any percolate api result. This issue any occurred when `.percolator` type is created on the fly.

Also made the call to PercolatorQueriesRegistry#enableRealTimePercolator and #disableRealTimePercolator synchronized, so that for the same shard the RealTimePercolatorOperationListener can't registered twice.