Provide utility function "file_is_newer_than" for results caching.
Simplify file load helper.
Added whats-new entry.  Slightly improved docstring.
Move 'tests.util.test_file_is_newer_than' into the unit-tests structure.
Tidied error case testing.
Merge pull request #787 from pp-mo/pickle_helper

Provide utility function "file_is_newer_than" for results caching.
Move concatenate operation from 'iris.experimental' into a CubeList method.
Merge pull request #783 from pp-mo/promote_concat

Moved concatenate from 'iris.experimental' to 'iris'.
Switch to setuptools and pre-load coastlines.
 - The python-distribute.org DNS entry no longer exists.
 - The distribute package has been merged back into setuptools.
Merge pull request #795 from rhattersley/setuptools

Switch to setuptools.
Added rolling window support for masked arrays
Merge pull request #793 from niallrobinson/rolling_window_masked

rolling_window on masked cubes
NF - Load reduced regular lat/lon grids from GRIB1.
NF - Generalise reduced GRIB loading to versions 1 and 2.

Also adds support for missing values and changes the interpolation
method to 1d linear interpolation along constant latitudes.
Improved latitude dimension construction and missing value handling.

Latitude dimension handling was incorrect, it now correctly
determines the incoming latitude dimension.

Missing values are handled in a way that avoids the missing value
clashing with a valid data value.
Updated test data reference in Travis configuration.