Change package.sh to specifically use BASH as the shell as newer Debian and OSX default to use a 100% POSIX shell that doesn't support `[[ ]]` for pattern matching, whereas BASH, KSH anD ZSH do and BASH is available on OSX and all Linux distributions (notably Fedora, CentOS, RHEL, Debian & Ubuntu).
Merge pull request #2 from gawainlynch/master

Make package.sh shell use more portable