Enable localisation of flash messages
Since Flask upgraded to 0.10, it's no longer possible to use
`lazy_gettext` to set `LoginManager.login_message`.

Add an optional `localization_function` argument/attribute to be called
with flash messages if the method is present.
Enable localisation of flash messages
Since Flask upgraded to 0.10, it's no longer possible to use
`lazy_gettext` to set `LoginManager.login_message`.

Add an optional `localize_callback` attribute to be called
with flash messages if the attribute is not None.
Merge branch 'master' of https://github.com/deanishe/flask-login