Build version6

• Redesign the build_version to run with Ext JS 6
• Single script to be used with all applications including plugin_dbui.
• Build process can be configure via the python package configure_build.py. It has to be installed in the main directory of your application.
• Add the option to --export-plugin.
• Change the option --plugins to --import-plugins.
• Review message, doc string, etc.
• Close #1 (closed)