Reexport `predicates` in crate root

[tgross35]

Would it be possible to pub use predicates in the crate root? Since the crate is somewhat fundamental to output testing, it would be convenient to have direct access. One dependency fewer to name in Cargo.toml with the added benefit of knowing the version is always correct.

I am surprised this hasn't been asked before... maybe I just couldn't find it.

[epage]

Predicates was intentionally left out of the - public API, wrapping things in newtypes and using predicates-core.