Renames exceptions to errors to avoid ImportError
Adds several bugfixes and improvements:

- Fixes the crawler bug that was only returning
  the first call results (appending instead of 
  extending a list);
- Fixes importer bug regarding coordinates;
- Fixes importer bug regarding the data import;
- Converts code to follow PEP8 styleguide
  (http://legacy.python.org/dev/peps/pep-0008/);
- Removes several useless comments.