IMPALA-2555: Allow download of thrift profile via Impala WebUI
IMPALA-2555: Allow download of thrift profile via Impala WebUI

This patch adds a new tab "Thrift Profile" to the query details
view in the impala web UI. Clicking on it downloads a thrift
representation of the query profile, which is gzip compressed and
base64 encoded.

Change-Id: I0efbc73bcb3904bb94c06f0a4ce591a75cb368bc
Reviewed-on: http://gerrit.cloudera.org:8080/1263
Reviewed-by: Bharath Vissapragada <f23dbca75acdac4082d6a05c290fc03565dada86@cloudera.com>
Tested-by: Internal Jenkins

michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,cloudera/Impala