Separate username/password from serverUrl

[danizen]

• Push version of committer-core and jest to latest
• Add test class
• Add xsd and xml file for tests
• Add usernam and password fields - not as far as @essiembre went with Mongo Data store factory class
• Adjust tests for username and password

[niels]

Thanks, @danizen!

Seeing how basic authentication is already supported (albeit differently) and in light of https://www.norconex.com/collectors/committer-elasticsearch/releases#a4.0.0-SNAPSHOT just having been released (https://github.com/Norconex/committer-elasticsearch/issues/4#issuecomment-301562216), I will leave this repository as-is except for bug fixes.

I now consider https://github.com/herimedia/norconex-committer-elasticsearch-rest to be deprecated in favour of the upstream https://www.norconex.com/collectors/committer-elasticsearch versions 4+.