Implemented Pre/Post Archive Script Events

The script events `pre-archive-cmd` and `post-archive-cmd` can be used
to perform any tasks necessary when archiving the composer project.

This functionality can be used to run unit test or and other build
process before archiving, and can be used to distribute the archive
when completed
updated documentation with pre/post archive events
Merge pull request #2629 from moranjk/master

Implemented Pre/Post Archive Script Events