mysql: set charset on server to utf8

Also, fix config location
Rename start.sh to run.sh
Update maintainer
Remove unused volumes
Change the condition of new installation

Check if directory /var/lib/mysql/mysql exists. If it doesn't exist,
start new installation procedure.

Other changes:
- change admin password
- add exec statement at the end of run.sh
- improve log messages
Add messages to show installation progress
Don't install package which is already installed