Allow deployment of the executable through maven repos.

Adds two new options:

<attachProgramFile>true|false</attachProgramFile>

if true, adds the created executable as a build artifact.

Due to the way maven handles artifacts, it will be named
${artifactId}-${version}.<program file type>. The program file type
can be set with

<programFileType>exe</programFileType> and defaults to "sh".

It is not possible to install or deploy and artifact without an ending
("type" in maven speak).
Merge pull request #7 from hgschmie/master

Allow deployment of the executable through maven repos.