fixes #245 - change 'extinction' argument to 'temperature'.
Update docs to reflect change of 'extinction' to 'temperature' (issue-245).
Merge pull request #245 from dshiga/issue-245

'extinction' incorrectly maps to temperature section of irsa_dust result
refactor _is_coordinate / _is_name tests to common location, and avoid
issue astropy#1727
isinstance tests fail; use other ways to test... (I prefered
isinstance..., but coordinates.Galactic !=
coordinates.GalacticCoordinates)
more isinstance -> equality tests
py3 compat?
Merge pull request #248 from keflavich/fix_coords_nov2013

Bug fixes for recent astropy coordinates changes
This test also fails in astropy 0.2.5
Merge pull request #249 from jwoillez/fix_new_astropy_stable

Small fix in Simbad test suite to make it pass with new astropy stable.
ukidss keeps track of response for error checking...
For region queries, moved parameter parsing from _args_to_payload to query_region_async

There is now a center dictionary passed between the two.
Made query_object_async use center as well.
In _args_to_payload, caller is not needed anymore.
Merged height and width keywords of query_region_async into a single box keyword.
Made radius keyword of query_region_async support annular region.
Removed keywords from query_constraints_async

The functionality is already present through **kwargs.
In addition, in Vizier language, keyword means catalog keyword, not
column filter.
_parse_dimension now only works with astropy.coordinates.Angle

This also preserves the unit requested in query_region when requesting
the '_r' calculated column.
Simplified columns and column_filters in VizierClass constructor and _args_to_payload.

Not related to this commit, but at this point query_contraints does not
work properly.
Made query_constraints use _args_to_payload.