use hash instead of type
use hash instead of type

https://stackoverflow.com/questions/592620/check-if-a-program-exists-from-a-bash-script

Couple of reasons:
* hash is used for multiple lookups
* type checks builtins as well (which we don't need)

ryanmjacobs/c,ryanmjacobs/c,ryanmjacobs/c,ryanmjacobs/c