madpack: Specifically use /bin/bash instead of /bin/sh
madpack: Specifically use /bin/bash instead of /bin/sh

In general /bin/sh is equivalent to /bin/bash, but not on ubuntu where
/bin/sh is actually /bin/dash.  This matters because the madpack script uses
`pushd` and `popd` which are bash-specific enhancements; on ubuntu this script
causes errors like:

    /usr/local/madlib/bin/madpack: pushd: not found
    /usr/local/madlib/bin/madpack: popd: not found

The fix is to specifically use bash.  For more info:
    http://askubuntu.com/questions/141928/what-is-difference-between-bin-sh-and-bin-bash

rvs/incubator-madlib,iyerr3/incubator-madlib,orhankislal/madlib,hpandeycodeit/incubator-madlib,orhankislal/incubator-madlib,rvs/incubator-madlib,lmatthieu/incubator-madlib,rashmi815/incubator-madlib,njayaram2/incubator-madlib,madlib/madlib,iyerr3/incubator-madlib,iyerr3/incubator-madlib,madlib/madlib,njayaram2/madlib,mktal/incubator-madlib,njayaram2/madlib,rashmi815/incubator-madlib,njayaram2/incubator-madlib,rashmi815/incubator-madlib,mktal/incubator-madlib,hpandeycodeit/incubator-madlib,orhankislal/madlib,njayaram2/madlib,lmatthieu/incubator-madlib,iyerr3/incubator-madlib,orhankislal/madlib,orhankislal/incubator-madlib,lmatthieu/incubator-madlib,rvs/incubator-madlib,madlib/madlib,njayaram2/incubator-madlib,madlib/madlib,iyerr3/incubator-madlib,apache/incubator-madlib,hpandeycodeit/incubator-madlib,njayaram2/madlib,lmatthieu/incubator-madlib,orhankislal/incubator-madlib,cooper-sloan/incubator-madlib,cooper-sloan/incubator-madlib,rashmi815/incubator-madlib,hpandeycodeit/incubator-madlib,cooper-sloan/incubator-madlib,mktal/incubator-madlib,apache/incubator-madlib,rvs/incubator-madlib,orhankislal/madlib,njayaram2/madlib,orhankislal/incubator-madlib,njayaram2/incubator-madlib,orhankislal/incubator-madlib,apache/incubator-madlib,apache/incubator-madlib,mktal/incubator-madlib,njayaram2/incubator-madlib,rashmi815/incubator-madlib,lmatthieu/incubator-madlib,rvs/incubator-madlib,cooper-sloan/incubator-madlib,cooper-sloan/incubator-madlib,apache/incubator-madlib,hpandeycodeit/incubator-madlib,madlib/madlib,mktal/incubator-madlib,orhankislal/madlib