[utils,franceinter] Add french months' names and fix extraction

Update of the "FranceInter" radio extractor : webpages HTML structure
had changed, the extractor didn't work. So I updated this extractor to
get the mp3 URL and all details.

youtube_dl/utils.py

@@ -91,6 +91,10 @@ ENGLISH_MONTH_NAMES = [
     'January', 'February', 'March', 'April', 'May', 'June',
     'July', 'August', 'September', 'October', 'November', 'December']
 
+FRENCH_MONTH_NAMES = [
+    'janvier', 'fevrier', 'mars', 'avril', 'mai', 'juin',
+    'juillet', 'aout', 'septembre', 'octobre', 'novembre', 'decembre']
+
 KNOWN_EXTENSIONS = (
     'mp4', 'm4a', 'm4p', 'm4b', 'm4r', 'm4v', 'aac',
     'flv', 'f4v', 'f4a', 'f4b',
@@ -1587,11 +1591,16 @@ def parse_count(s):
     return lookup_unit_table(_UNIT_TABLE, s)
 
 
-def month_by_name(name):
+def month_by_name(name, lang='en'):
     """ Return the number of a month by (locale-independently) English name """
 
+    name_list = ENGLISH_MONTH_NAMES
+
+    if lang == 'fr':
+        name_list = FRENCH_MONTH_NAMES
+
     try:
-        return ENGLISH_MONTH_NAMES.index(name) + 1
+        return name_list.index(name) + 1
     except ValueError:
         return None