base: disable populate bibupload task

* As it's not needed on labs.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
Gravatar fix

* Set GRAVATAR_DEFAULT = "https://invenio-demo.cern.ch/img/user-icon-1-20x20.gif"

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
accounts: disable local login

* Set CFG_DISABLE_LOCAL_LOGIN.

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>