refactor flask_cors as optional

debian/control

@@ -11,6 +11,6 @@ Package: python-pygeoapi
 Architecture: all
 Depends: ${misc:Depends}, ${python:Depends}, python-pkg-resources, python-click, python-flask, python-yaml
 Suggests: python-elasticsearch, python-geojson, python-shapely
-Homepage: https://github.com/geopython/pygeoapi.git
+Homepage: https://github.com/geopython/pygeoapi
 Description: pygeoapi provides an API to geospatial
  data

pygeoapi/flask_app.py

@@ -34,7 +34,6 @@ import click
 import yaml
 
 from flask import Flask, make_response, request
-from flask_cors import CORS
 
 from pygeoapi.api import API
 
@@ -130,7 +129,8 @@ def serve(ctx, debug=False):
     if not api_.config['server']['pretty_print']:
         APP.config['JSONIFY_PRETTYPRINT_REGULAR'] = False
 
-    if api_.config['server']['cors']:
+    if 'cors' in api_.config['server'] and api_.config['server']['cors']:
+        from flask_cors import CORS
         CORS(APP)
 
 #    setup_logger(CONFIG['logging'])

requirements-dev.txt

@@ -1,3 +1,4 @@
+flask_cors
 coverage==4.5.1
 docutils==0.14
 flake8==3.5.0

requirements.txt

@@ -1,6 +1,5 @@
 click
 elasticsearch
 Flask
-Flask_Cors
 PyYAML
 Shapely