let PrintableError accept format arguments
let PrintableError accept format arguments

Summary:
`PrintableError('...'.format(...))` is a very common pattern. This
simplifies things a bit.

Reviewers: sean

Differential Revision: https://phabricator.buildinspace.com/D199

nivertech/peru,enzochiau/peru,nivertech/peru,olson-sean-k/peru,oconnor663/peru,enzochiau/peru,ierceg/peru,ierceg/peru,scalp42/peru,olson-sean-k/peru,oconnor663/peru,scalp42/peru,buildinspace/peru,buildinspace/peru