Fix README following changes in keys and update classifiers

Author: werdeil

README.rst

@@ -28,16 +28,16 @@ Here below the new configuration options available in the `pibooth`_ configurati
     [QRCODE]
 
     # Prefix URL for the QR code
-    qrcode_prefix = "https://github.com/pibooth/pibooth"
+    prefix_url = "https://github.com/pibooth/pibooth"
 
     # Use only one URL for all photos (one QR code linking to the album)
     unique_url = True
 
     # QR code foreground color
-    code_foreground = (255, 255, 255)
+    foreground = (255, 255, 255)
 
     # QR code background color
-    code_background = (0, 0, 0)
+    background = (0, 0, 0)
 
 .. note:: Edit the configuration by running the command ``pibooth --config``.
 

setup.py

@@ -27,8 +27,10 @@ def main():
             'License :: OSI Approved :: GNU Affero General Public License v3',
             'Operating System :: POSIX :: Linux',
             'Programming Language :: Python :: 2.7',
-            'Programming Language :: Python :: 3.4',
-            'Programming Language :: Python :: 3.5',
+            'Programming Language :: Python :: 3.6',
+            'Programming Language :: Python :: 3.7',
+            'Programming Language :: Python :: 3.8',
+            'Programming Language :: Python :: 3.9',
             'Natural Language :: English',
             'Topic :: Multimedia :: Graphics :: Capture :: Digital Camera',
         ],