Bar demo2 improve

Prompted by this: http://stackoverflow.com/questions/18369798/how-to-get-ticks-on-both-sides-at-same-tick-locations/18371449#18371449

The demo looks like it relies on some auto-range magic to work correctly.  Made more fool-proof.

Not sure if this should go against 1.3.x or master, targeted 1.3.x because (I think) it is easier to move the other way.

Also include pep8 clean-up