Remove legacy classes which ensure backward compatibility with the FLX security plugin for ElasticSearch.

Remove classes from packages:

1. com.floragunn.searchguard.user
2. com.floragunn.searchguard.support

Visibility of method com.eliatra.suite.securityplus.user.Attributes#addAttributesByJsonPath(java.util.Map<java.lang.String,com.jayway.jsonpath.JsonPath>, java.lang.Object, java.util.Map<java.lang.String,java.lang.Object>) should be changed from public to package private.