add expectation for not overwriting files if set to :never
add a PublicAPI spec file, add on_conflict option to Borrower::put
reorganize spec helpers a bit
finish spec & implementation for conflict handling on the PublicAPI#put method
pass the on_conflict option down to PublicAPI#put from `borrow`
add to readme and changelog
try and skip silencing stdout in Travis-CI
add new rbx to travis.yml
add note about ruby versions, revert rbx (issues with simplecov)
bump version