updated HELIO link to the updated registry which is not linked to a particular machine
Merge pull request #1080 from dpshelio/heliofix

HELIO url update
Merge branch 'master' of https://github.com/sunpy/sunpy into coordinates-framework
Minor fix for HelioGraphicStonyhurst class.
Added if-clause for when args and kwargs are both specified.
Deals with the case when one of hlon/hlat is specified in args and the rest in kwargs.