User Defined Aggregate (UDA) function support in Geode OQL

[Anilkumar Gingade <ag...@pivotal.io>]

Hi Geode Devs,

To enhance Geode query functionalities; we had started initiative to
support Aggregate and UDA functionalities using a common frame work.

The spec for this can be found at:
https://cwiki.apache.org/confluence/display/GEODE/OQL+Aggregate+functions+and+UDA

As part of first phase implementation, we added common frame-work and
support for standard aggregate functions like Min, Max, Avg and Sum, which
is available in the Geode develop branch.

As a second phase implementation, we have added support for UDAs which is
available as feature branch.

feature/GEODE-1269

We are looking for input, comments and contribution to that UDA
functionality, try it and let us know your feedback.

Thanks,
-Anil.