Analytic Fns: BE support for range unbounded on both sides and range offsets fail analysis

1) Adds BE support for RANGE windows between UNBOUNDED PRECEDING to
   UNBOUNDED FOLLOWING.
2) RANGE windows with offset boundaries fail analysis because they're
   not supported by the BE yet.

Change-Id: I734575eb87c909d09d24c4df028023f3b50d3cb5
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4442
Reviewed-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: Matthew Jacobs <mj@cloudera.com>