Fix dms and hms to return a tuple of arrays -- this allows for round-tripping.
Merge pull request #1307 from lpsinger/iterative_wcs_whatsnew

Record new method `WCS.all_world2pix` in changelog
Fix crash in Angle.to_string() with a composite unit
Fix error on Numpy 1.5
Merge pull request #1006 from mdboom/unit/quantity-subclasses

Make `Angle` a `Quantity` subclass
Merge pull request #1303 from mdboom/setup/make-update_package_files-generic

Make update_package_files future-proof
Merge pull request #1308 from vterron/master

Add missing verb ("is")
Merge pull request #1289 from mdboom/unit/speed_optimizations

Improves the speed of units
rebase
add constraints tests
fix linear attribute
remove an erroneous  import statement
Address comments by @iguananaut; add m ore tests
Rebased
remove a commented line (and start a new travis build
Revised the list of models with constraints. Also converted rotations classes to using the new Parameter object (somehow missed this the first time).
Use RandomState in iterative tests
remove a commented line
Adds rudimentary __str__ and __repr__ representations for NDData objects.
Fix misspelled word ("Deletetion")