Created new installscript and updated + extended README.md with screenshots

1. The new installscript contains sudo and doesn't need to be executed by root user
    1. It also installs ADBGUI in a way it can be executed by a normal user, therefore fixes #4 
    2. New default ADBGUI port is 8181, set in dbm.cfg.
    3. The old install script is still there and works (install.debian.sh)

2. New README.md now contains screenshots and instructions first steps for ADBGUI admins
   1. Also the install instructions now are quite shorter, because of the new install script.