added to mail settings, to send emails to log file, useful for debuging
Optimized images

All images optimalized via PNGGauntlet. The image quality unchanged, but
the files became smaller.
Update jQuery files

Demo theme: v1.10.2 -> v1.11.1
Backend: v2.0.3 -> v2.1.1
Furthermore I renamed the jquery-2.0.3.min.js file because of easy to
update jQuery in future.
Merge pull request #798 from nnmer/master

added to mail settings, to send emails to log file, useful for debuging
Merge pull request #800 from gergo85/master

Optimized images and update jQuery
Minor refs #798