Don't use user/password cache from the login page

The idea is to always use memcached for credentials to avoid hitting
the authentication backend on every click but to check with the auth backend
for every login requests.

This should fix #2169

While there, fix whitespace (killtab)
don't use cache for login page
Merge 'tests/authcache' - don't use cache on login
Updated NEWS
Remove x-webobjects-remote-host from apache conf

SOPE now handles this on its own by setting x-webobjects-remote-host
to the content of the x-forward or x-forwarded-for headers if it wasn't defined
whitespace (tabkill)
Plug sieve connection leak

Fixes #2228
Fix from 'bofhus'
Avoid going out of bounds for special URL chars ending mail contents.
Add missing localizable string
Log x-webobjects-remote-host  in login process

Most of the time, the remote-host will contain data from the x-forwarded-for header.
Which could have more than one ip in it if the request went through multiple proxies.
eg. x-forwarded-for: real.client.ip, load.balancer.ip
Update Polish translation
Update Finnish translation
Add example configuration for fail2ban

From Arnd Brandes. (#2229)
Fix segfault in SOGoSieveManager.m
Use SOGoSystemDefaults in all tools

sogo-ealarms-notify and sogo-slapd-sockd will now be able to use sogo.conf
Fixes #2226
Add example apache configuration for apple AB
Update Danish translation
Ensure we hit the cache with hex-formatted keys.
Alse use hex-formatted keys for deleted mails.
Fix issue with exceptions in repeating events

Fixed the display of an exception when its recurrence id is outside the
current view.