Issue 4488 - Add support for JSON page front matter

cms/utils.py

 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-present eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ skipping 74 matching lines @@
             value = value.strip()
             if value.startswith('[') and value.endswith(']'):
                 value = [element.strip() for element in value[1:-1].split(',')]
             metadata[name.strip()] = value
             length += len(line)
 
     if length > 0:
         # Need to preserve line numbers for jinja2 tracebacks
         cutoff = m.end() if m else length
         source = '\n' * source.count('\n', 0, cutoff) + source[cutoff:]
+
     return metadata, source
 
 
 def get_page_params(source, locale, page, format=None, site_url_override=None,
                     localized_string_callback=None):
     from cms.converters import converters
 
     # Guess page format if omitted, but default to Markdown for friendlier exceptions
     if format is None:
         for format in converters.iterkeys():
@@ skipping 61 matching lines @@
     return params
 
 
 def process_page(source, locale, page, format=None, site_url_override=None,
                  localized_string_callback=None):
     from cms.converters import TemplateConverter
 
     params = get_page_params(source, locale, page, format, site_url_override,
                              localized_string_callback)
     return TemplateConverter(*params['templatedata'], params=params)()