Create docker images for app and db

[valasek]

Expected output:

• two docker images one for db one for the main app, as minimal as possible,
• db will be backed up in an external folder and timesheet config and import/export data will be in an external folder as well

Inputs

• https://blog.golang.org/docker
• https://blog.codeship.com/building-minimal-docker-containers-for-go-applications/
• https://github.com/miguno/golang-docker-build-tutorial