adding annotation support to jetty 9.1 section

as I wrote in issue 106, changes are:
added jetty-annotations to library dependencies
added default (hardcoded, maybe, that's not good) default configuration
added AnnotationConfiguration to default configuration and configuration with config file
added setExtraClassPath
added webInfIncludeJarPattern setting

example of my webInfIncludeJarPattern setting usage:
```
webInfIncludeJarPattern in Compile := Some( """.*com\.simplesys.*/*\.jar$|.*ru\.simplesys.*/*\.jar$|.*/classes/.*""")
```

Fixes #106