py-cftime: new package (#10066)

* py-cftime: new package

* Added dependency on py-setuptools, and version range for py-cython, thanks to the ever-vigilant @adamjstewart

var/spack/repos/builtin/packages/py-cftime/package.py

+# Copyright 2013-2018 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+from spack import *
+
+
+class PyCftime(PythonPackage):
+    """Python library for decoding time units and variable values in a
+       netCDF file conforming to the Climate and Forecasting (CF)
+       netCDF conventions"""
+
+    homepage = "https://unidata.github.io/cftime/"
+    url      = "https://github.com/Unidata/cftime/archive/v1.0.3.4rel.tar.gz"
+
+    version('1.0.3.4', sha256='f261ff8c65ceef4799784cd999b256d608c177d4c90b083553aceec3b6c23fd3')
+
+    depends_on('py-setuptools@18.0:', type='build')
+    depends_on('py-cython@0.19:', type='build')
+    depends_on('py-numpy', type=('build', 'run'))