guard against content-type http header not being present

feediverse.py

@@ -167,7 +167,7 @@ def collect_images(entry, generator=None):
     for url in urls:
         try:
             resp = http.request('GET', url, preload_content=False)
-            if resp.headers['content-type'].startswith(("image/", "video/")):
+            if resp.headers.get('content-type', '').startswith(("image/", "video/")):
                 images.append(resp)
                 # IMPORTANT: Need to release_conn() later!
                 if len(images) >= MAX_IMAGES:

setup.py

@@ -5,7 +5,7 @@ with open("README.md") as f:
 
 setup(
     name='feediverse',
-    version='0.2.0',
+    version='0.2.1',
     python_requires='>=3.3',
     url='https://github.com/edsu/feediverse',
     author='Ed Summers',