add session gc vars to configurable values

session.gc_divisor and session.gc_probability are needed e.g. for Horde to work correctly
minor fixes in installation-class, better error-handling

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
Merge pull request #172 from seidler2547/master

add session gc vars to configurable values for php-fpm
added possibility to enable slowlog for fpm-users in the php-config (domain based logs), fixes #1051

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
use better defaults for fpm-slowlog settings, refs #1051

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
Create readme.md
fix mysqldump for backup (if db exists) on install-process

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>
fix wrong error message if customer-loginname has invalid characters when unix-names == 1, thx to Sephi

Signed-off-by: Michael Kaufmann (d00p) <d00p@froxlor.org>