Adding support for percolating on rolling indices

By having an index called _global with mapping that match the mapping of the rolling indices in your system, and registering all percolator queries against this index, you can percolate and index with percolation and get results for all registered queries without worrying about registering all query on all indices in your system.

See discussion here: http://elasticsearch-users.115913.n3.nabble.com/Percolation-while-indexing-to-rolling-indexes-logs-td4028858.html