Add CI tasks that can be run in a Docker container

Enables a Docker based build server to create logsearch dev releases using a command like:

```
docker build -t $JOB_NAME $(pwd)

docker run -e BOSH_TARGET=https://xx.yy.zz.bb:25555 -e BOSH_USER=sudobot -e BOSH_PASSWORD=$SUDOBOT_BOSH_PASSWORD -v $(pwd):/workspace -t $JOB_NAME rake dev_release:create_and_upload_and_deploy
```

No; when creating a dev release for the first time (ie, on a clean buiildserver repo) we have to specify a release name