Handled documentation requirements installation.

.travis.yml

@@ -76,6 +76,13 @@ install:
       conda install --quiet --file ${CONDA_REQS_FILE};
     fi
 
+
+  - >
+    if [[ "${TEST_TARGET}" == 'doctest' ]]; then
+        conda install --quiet --file requirements/docs.txt
+    fi
+
+
   # JUST FOR NOW : Install latest version of iris-grib.
   # TODO : remove when this release is available on conda-forge.
   - if [[ "$TEST_MINIMAL" != true ]]; then

requirements/docs.txt

@@ -0,0 +1 @@
+sphinx

setup.py

@@ -1,14 +1,13 @@
 from __future__ import print_function
 
 from contextlib import contextmanager
-from distutils.core import Command
 from distutils.util import convert_path
 import os
 from shutil import copyfile
 import sys
 import textwrap
 
-from setuptools import setup
+from setuptools import setup, Command
 from setuptools.command.develop import develop as develop_cmd
 from setuptools.command.build_py import build_py