IMPALA-939: Regex should match anywhere in string.

Change-Id: I8dcd337c3b06b632017270670a4f199ec7ada648
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2296
Reviewed-by: Victor Bittorf <victor.bittorf@cloudera.com>
Tested-by: jenkins
Increase default_pool_max_requests in run-all-tests.

Temporarily increase the cap on max requested queries while running tests to unblock
builds. Currently, the exhaustive runs always fails, and there are some intermittent
failures in the core runs.

Change-Id: I26b9ce343d72bab7687e49f7dbd7bf3bf655a294
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2323
Reviewed-by: Ishaan Joshi <ishaan@cloudera.com>
Tested-by: jenkins
IMPALA-888: Drop union operands with constant conjuncts evaluating to false.

This patch simplifies the complex slot materialization logic for unions by
making the materialization independent of conjuncts assigned to MergeNodes.
When 'pushing down' predicates into union operands, we drop union operands
with constant predicates evaluating to false. Constant predicates that
evaluate to true are simply ignored.

Change-Id: I0e7ccfb206bed29db2b5d667e2bb61310980e80a
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2270
Reviewed-by: Alex Behm <alex.behm@cloudera.com>
Tested-by: jenkins