Indicators base url set on class instead of global

as APIs all have different base urls
Add climate connection w/historical functions
Add climate modelled and stat calls
Fix description spelling in setup.py
Del wbpy in __init__ so internals not accessible

Want the interaction to be with ``wbpy.Indicators()``, ``wbpy.Climate()``, etc,
rather than being able to access all
the internal imports in wbpy.wbpy, eg. ``wbpy.wbpy.logging``, ``wbpy.wbpy.os``.
I suspect there is a better way to accomplish this.
Update setup.py metadata
Move tests to parent directory
Full support for iso alpha-2 country codes
No need for nested 'value' subkey in info dicts
Fix unicode encode error
Remove values already used as indicator keys
Return metadata dicts with Climate results

Unlike the Indicators API, you can't make a call to get the Climate IDs
for models, statistics etc, so those definitions are made accessible as
properties on the Climate class.
Handle ensemble_percentile arg properly
Fix deletion of climate 'ensemble' gcm definition
Use plural ensemble_percentiles as arg is list
Treat 'ensemble' as any other gcm id

so the gcm arg is always a list, and results of ensemble and non-ensemble calls
are merged. 'Ensemble' and other gcm args no longer mutally exclusive.
Update climate docstrings
Remove countries from indicator metadata dict

I don't think there's any point duplicating this info. The indicator IDs are
useful as they're not in the results and (I assume) they're unique to the WB,
but the ISO codes are already in the result keys, and you can easily lookup
countries by using get_countries() or pycountry.
'metadata' is better term than 'info'
Add date pairs to climate metadata