Merge remote-tracking branch 'upstream/staging' into map
Merge pull request #477 from sunpy/staging

Time to sync master with staging again
merge from upstream (map refactor)
fix to map grid plotting which got lost in refactor
fixed bug in plotting of compositemaps
Merge pull request #489 from ehsteve/map

A few bug fix for refactor and plotting
Merge pull request #488 from Cadair/pyfits

Deprecate pyfits in place of astropy
Fix behaviour when DummyAttrs remain in query.
Fix missing EOL.
Remove DummyAttr from HEK walker.
Add tests for HEK.
Make spectrogram plotting consistent.

Lacks updated docs!
Add download progress bar.
Fix downloader deadlock.
Fix refactor regression.

clip_freqs no longer updated the freq axis.
Update docs.
Fix tests.
Improve tests
Add a word about Anaconda.
Add word about multiple Python envs.