Create a shell script to automate generating docs

Currently docs are generated manually. We should be able to automate it with a shell script, which does the following:

• run maven javadoc plugin in those modules that need javadocs generated
• create a soft link "latest" pointing to the current docs directory
• create a index.html for the user guide that redirects to JBeret User Guide page at gitbook.com
• run maven miredot plugin to generate REST API docs in jberet-rest-api module
• transfer all docs content to docs.jboss.org/jberet site
• etc