The updates for unicode and Python 3 in RBTools 1.0 changed the type of

the string passed into getpass from a bytestring to unicode.

Unfortunately, with Python 2.7 on Windows, this fails. This change fixes

all callers up to pass in str instead, which should work correctly for

both Python 2.7 and 3.x.

Verified that getpass worked correctly (on Linux). My Windows

environment isn't in a usable state right now.