Add alias in impala-config.sh to gerrit-merge-verify script
Add alias in impala-config.sh to gerrit-merge-verify script

This alias makes it easy to verify and merge Gerrit changes

Change-Id: Idb0b5c3e6c825721e375bdf0c86b5975df1ed4b9
Reviewed-on: http://gerrit.ent.cloudera.com:8080/836
Reviewed-by: Ishaan Joshi <d1d1e60202ec9f2503deb1b724986485a125d802@cloudera.com>
Tested-by: Lenni Kuff <724b7df200764f5dc1b723c05ee6c6adabd11bb1@cloudera.com>

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