fix order of docker commands

In Dockerfile the FROM commad should be alway the first 
but when add dockerExposedPorts or dockerExposedVolumes those are the first line in the file.

```
[info] Step 0 : EXPOSE 9000
[error] 2014/07/14 12:46:23 Please provide a source image with `from` prior to commit
[trace] Stack trace suppressed: run last docker:publishLocal for the full output.
[error] (docker:publishLocal) Nonzero exit value: 1
````