Add Script and DotExpander Pipeline Processors

[niemyjski]

• GeoIp isn't specified in the elastic docs, if these are plugins, they should mention it in the xml docs
• Attachment isn't specified in the elastic docs, if these are plugins, they should mention it in the xml docs

Support for Script and Dot Expander processors are missing.

[russcam]

Merged into 5.x and master from #2361

[niemyjski]

Thanks @russcam!