[DEV] Quantity formatting shortcut for values.
Docs for new-style Quantity string formatting
Added Quantity format strings to CHANGES.rst
Added a reference for astropy-units-format
Fixed a typo in CHANGES.rst
Improvements to Quantity format documentation.
Quantity formatting unit tests.
Quantity formatting documentation for arrays
Fix for {} vs {0} for quantity array format docs
Merge pull request #1383 from alexrudy/quantity-format

Quantity format