Add Docker support

This commit adds a Dockerfile that can be used to build a Docker image
for running LSTU.
9 jobs from docker-support in 12 minutes and 26 seconds (queued for 50 seconds)
latest
Status Job ID Name Coverage
  Sqlite
passed #126023
sqlite1

00:03:45

passed #126024
sqlite2

00:03:52

passed #126025
sqlite3

00:03:56

 
  Postgresql
passed #126026
postgresql1

00:03:57

passed #126027
postgresql2

00:01:00

passed #126028
postgresql3

00:01:02

 
  Mysql
passed #126029
mysql1

00:01:16

passed #126030
mysql2

00:04:21

passed #126031
mysql3

00:01:28