[CALCITE-93] Calcite RPC server;
[CALCITE-94] Remote JDBC driver

Add module, calcite-avatica-server. HttpServer is an RPC server that listens on port 8765 for JSON requests over HTTP.

We can now execute basic queries, and schema and catalogs metadata requests, over request-response.

Change interface AvaticaPrepareResult to class Meta.Signature.

Move DateTimeUtil to Avatica and rename to DateTimeUtils.

Linq4j.iterableEnumerator checks whether the Iterable is already an Enumerable; IterableEnumerator calls close() if the Iterator implements Closeable.

Add test case for [CALCITE-508] (not fixed yet).

For remote testing, allow CalciteAssert to test all connections, not just CalciteConnection.
Add a model that has lattices and works against HSQLDB.
[CALCITE-512] Add GROUP_ID and GROUPING_ID functions

Upgrade to quidem-0.2 (fixes right-justification of numeric columns)
[CALCITE-511] copy method in LogicalAggregate not copying the indicator value properly
fixes #26