reader: restore go1.0 compatibility
implement io.Copy interfaces: io.ReaderFrom and io.WriterTo
Merge pull request #14 from bmatsuo/copy-interfaces

implement io.Copy interfaces: io.ReaderFrom and io.WriterTo
fix build error: panic instead of (unreachable) return
Merge pull request #15 from bmatsuo/fix-build

fix build error: panic instead of (unreachable) return
add travis
fix travis script