ext: SQLALCHEMY_ECHO default switched off
ext: SQLALCHEMY_ECHO default switched off

* Set SQLALCHEMY_ECHO=False as default value.
  (closes inveniosoftware/invenio-app-ils#19)

Signed-off-by: Leonardo Rossi <5460ec99b71a72e7693c4088b5c2585e76e1c857@cern.ch>

inveniosoftware/invenio-db,inveniosoftware/invenio-db