Using an array ref to specify class attributes

This allows us to specify multiple attributes with a specific set of default
options.
location_type is now an instance attribute
location_ssid is now an instance attribute
Converting remaining variables to share into instance attributes
[lib] using a Hotspotz namespace for classes

This will help to separate various concerns into various classes, which at
present are only within one class.
[lib] Extracting location-related code into its own class