Remove scraper initialization in default parameter

These get evaluated on instantiation, hence taking load time.
Seems better to test if it is None, and then initializate it,
which was the original intention. Now instantiation should be
way faster.
Remove Zaragoza Bizi from bizi declaration

They've changed the system for one synchronous, same as Bicing.
For now it is removed from here, until we decide what to do with
this.

Mexico EcoBici works for now