Fixes #166. Add raw=True when parsing passwords.

When parsing .pyrax, we should set the raw=True argument on
ConfigParser.SafeConfigParser.get on key or password fields, allowing percent
signs to be used there. Without this, users get
InterpolationSyntaxError. Switching from SafeConfigParser to
RawConfigParser would do the same thing, but it's backwards incompatible
because we could have people relying on interpolation elsewhere in their
config files.
Merge pull request #167 from briancurtin/working

Fixes #166. Add raw=True when parsing passwords.