Remove "create language" from install instructions

Newer versions of postgres seem to have plpgsql installed on new databases
by default, so it just causes an error and confuses the user.
Use DATABASE_NAME in local_settings.py.default

Within local_settings.py the DATABASES dictionary is not defined,
although we have partly defined it in django_settings.py.  Using
the old style DATABASE_NAME instead of DATABASES['default']['NAME'] works
here because we have code to merge old-style settings like this in
settings.py.
Add numpy to pip requirements

It's needed for the lottery.
Update libmemcached6 to libmemcached10

The libmemcached library keeps changing and is not always backwards
compatible.  This commit updates the package name so the package list will
work in Ubuntu 13.04.