Fixes #343 by defaulting to OrderedDict in CCDData.meta.setter

[MSeifert04]

See #343

CCDData.meta.setter will initialize an empty collections.OrderedDict in case the new value is None.

This is because NDData implements meta-checks as part of the setter itself (astropy >= 1.2) instead of during __init__ (astropy < 1.2).

[MSeifert04]

@crawfordsm I just found a note regarding this PR and that I didn't do a changelog because there was no appropriate section in the Changes.rst file.

Will this PR need a Changelog and if so should I add the section myself? and which version would come next?

[crawfordsm]

Okay, I've updated the change log to include a 1.0.2 release which would be the next bug-fix release and the 1.1 release which would be the next major release. This should probably go under 1.0.2 as it probably should be back dated to correspond to the astropy 1.2 release.