Added function to load a Surfer ascii grid

I until need to write some conditional test
Simplified implementation
Testing a generic way to read grd file
Fixed load function
Deleted a white line
Deleted another white line
Added io_surfer.py into cookbook

I'll change the url part when `fetch_bouguer_alps_egm()` will done
Added `fetch_bouguer_alps_egm()` in io.py
Using io.fetch_bouguer_alps_egm() in io_surfer reciple
Minor corrections
Removing logger, logger.get, log.info etc...
Minor corrections (again)
Docstring description
Minor corrections on docstrings
Merge pull request #33 from hbueno/grid

Added function to load a Surfer ascii grid