Build directory configuration parameter was added

It might be handy to make a build in the workspace and there's no reason to build it somewhere else.
That's why the build would be done in a workspace and, just to have an ability to specify custom build directory – an additional configuration parameter was added.
Artifacts archiving step has been made optional.

You wouldn't always want to archive artifacts on that step. That's why it should be possible to skip that step in the builder.