Support for script condition

[beowulfenator]

As mentioned in the PR #111, supporting a script condition is a nice feature. That PR, however is incomplete. I'll close the PR and keep the issue here in case somebody decides to implement this.

[randomsymbols]

There is no support for script object in Command::update. Everything is treated as a doc object, is there a particular reason for that? It seems easy to support it - just not to enclose the $data into doc sub array.