add gems bin/ to PATH; refs #5
remove pry require; development dependency

refs #5
shell portability; tested against bash and dash

succeeds when running ``checkbashisms``

refs #5
use $VAR instead of ${VAR}; no var manipulation
reorder bundle arguments

apparently --deployment needs to go last otherwise --path, --binstubs,
and --without do not have any effect

using bundle on $PATH since it is set up in env.sh

refs #5