FIX: repair regression due to using double underscore prefixes in variable names

* __VARs are name mangled by Python when used within classes
* URLref: [Python - Style Guide - Names to Avoid] http://www.python.org/dev/peps/pep-0008/#names-to-avoid @@ http://archive.is/fF6T5 @@ http://webcitation.org/6Mf5njTC1
FIX: repair regression in use of station_list.getLabel()