Use \b instead of \r for erasing

This allows the spinner to appear at the end of an already printed line
without having to set that as the prefix.
Merge
Start no longer returns error
Merge
Merge branch 'master' of https://github.com/briandowns/spinner into nocr

Conflicts:
	spinner.go
	spinner_test.go
Switch from carriage return to backspace

Allows for printing arbitrary text through normal means on the same line
as a spinner with expected behavior.
Merge pull request #12 from millere/nocr

Switch from carriage return to backspace