Bump numcodecs requirement to 0.5.3

As `numcodecs` 0.5.3 is the first release of `numcodecs`, which only
uses `pytest` without `nose`, bump the `numcodecs` requirement from
0.5.2 to 0.5.3. This way `zarr` can be tested without `nose` as a
dependency. Should help ensure that `nose` usage doesn't creep back into
the codebase.

Author: jakirkham

requirements_dev.txt

@@ -16,7 +16,7 @@ mccabe==0.6.1
 monotonic==1.3
 msgpack-python==0.4.8
 nose==1.3.7
-numcodecs==0.5.2
+numcodecs==0.5.3
 numpy==1.13.3
 packaging==16.8
 pkginfo==1.4.1

setup.py

@@ -26,7 +26,7 @@
         'asciitree',
         'numpy>=1.7',
         'fasteners',
-        'numcodecs>=0.5.2',
+        'numcodecs>=0.5.3',
     ],
     package_dir={'': '.'},
     packages=['zarr', 'zarr.tests'],