Eventually, there will probably be a `crate` visibility specifier that
does the same thing as `pub(crate)`. This commit replaces `pub` with
`pub(crate)`, so when `crate` is available we can easily switch to it.
* Run integration tests on multiple shells
To make sure that I don't break tests for shells other than my
dev-box's `sh` and the `sh` on travis, each integration test case
now runs using `sh`, `dash`, and `bash.