Adds exception management in language code access

tracim/test.ini

 # sqlalchemy.url = mysql+pymysql://tracimuser:tracimpassword@127.0.0.1/tracimdb_test
 sqlalchemy.url = sqlite:///tracimdb_test.sqlite
 use = config:development.ini
+lang = fr
 
 [app:main_without_authn]
 use = main

tracim/tracim/lib/helpers.py

     - asked by the request to the server,
     - supported by Tracim.
     """
-    return tg.i18n.get_lang(all=False)[0]
+    # TODO - A.P - language code access from test environment
+    # try based workaround instead of raw get language call for test
+    # environment only, this should be set with tg.i18n.set_lang in
+    # be I was unable to achieve that.
+    try:
+        result = tg.i18n.get_lang(all=False)[0]
+    except:
+        result = 'en'
+    return result
 
 
 def get_with_timezone(