CBQE-2377 add support install debian7
in install script

Change-Id: If718555cfab85de20f2c3484b375e7384edf043a
Reviewed-on: http://review.couchbase.org/40545
Tested-by: Thuan Nguyen <soccon@gmail.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Thuan Nguyen <soccon@gmail.com>