Added some git aliases

git alias
    will show all registered git aliases
git ignore <file>
    will ignore a file from staging
git ignorenot <file>
    will not ignore a file from staing anymore
git ignoreshow
    show all files that are ignored from staging
Added last-update to .gitignore for future updates
Added simple update functionality into install.sh

The script will stop installing now if the settings already exists and
try to update the settings instead.

The script will also handle the user-configuration now as it's own.
Made bin/monitor more flexible

monitor know 2 new commands now
monitor workl
    This gives a simple work arround for the buggy lenovo workstation of
    the t440.
monito extendl
    The monitor will extend to the left instead of right side
Quit the concept to assign common applications to specific screens

Removed all assignments of applications to screens from the i3-config
Replaced the names of different screens by numbers

Removed the names of screens due to the quited concept of assiging
application to screens
Changed shortcut to lock the screen to Super+Ctrl+Shift+L
Changed i3-laucher call
Changed sound-bindings for keyboard

This change has to be validated with other devices
Added st as shortcut for git status
Added environment specific aliases to bash