Always use Memcached backend when configured thus
Always use Memcached backend when configured thus

In the past we ignored Memcache errors by testing for a connection.
Connection errors were suppressed and a fallback "Blackhole" backend was
chosen.

To make the whole process more explicit, we no longer suppress any
errors and just crash early when Memcached is configured but not
available. You can turn off Memcached by configuring `NULL` as value for
constant `MEMCACHE_PORT` or `MEMCACHE_HOST`.

grrr-amsterdam/garp3,grrr-amsterdam/garp3,grrr-amsterdam/garp3,grrr-amsterdam/garp3