Uses ugettext_lazy to delay translation; reworks the __repr__
method to avoid using the translated form; and changes the
unicode method of the HorizonComponent class to actually return a
string coerced to unicode rather than a proxy object.
In the process, many more strings which had been missed have been
marked for translation.
Fixes bug 910297.
Change-Id: Ie8d10a928b0419313e6c54b0eff7a3a37299ca83
ab71aff23f