Admission controller: logging improvements

Some of the less verbose debug information is now log level 2. Also improved
the debug message logged when a request comes in to make it easier to read.

Change-Id: I0ab96d12f94ee52910995d85328aa401a9c77a65
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1897
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins
[CDH4] Update cdh4-extras

Updates a few of the Yarn server classes we use in cdh4-extras that have
changed.

Change-Id: I34d2a660cb9b4d8b0092bed2a130bd2f9590504c
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1893
Reviewed-by: Henry Robinson <henry@cloudera.com>
Tested-by: jenkins
IMPALA-879: impalad crashes while trying to serialize a runtime profile

The problem appears to be that query events in the runtime profile
are also exposed through QueryExecState, and there is no synchronization
to guard against corruption - impalad crashed while attempting to serialize
and compress a corrupted profile

This patch adds a lock to the EventSequence class to guard against
concurrently adding and reading events.

Change-Id: Iceda7ee5fb26bc82c8562447918150427c75779d
Reviewed-on: http://gerrit.ent.cloudera.com:8080/1912
Reviewed-by: Nong Li <nong@cloudera.com>
Tested-by: jenkins