System properties can override etc/*.properties
Optional override config with environment vars

-Dapplication.name=$CROWD_APP_NAME
-Dapplication.password=$CROWD_APP_PW
-Dapplication.login.url=$CROWD_APP_URL
-Dcrowd.server.url=$CROWD_URL
Updated path to target/*jar
ignore log/ and work/
Use `exec java` so that  ctrl-c in Docker works
Dockerfile for crowd-ldap-server
Updated README, also described Docker