"Access-Control-Allow-Headers" to make it work with Kibana

In 'AllPermsRealm' class, replaced System.outs with log.debug statements

milestone. Kibana uses a generic search query such as
http://elasticsearchhost:9200/testindex1/_search. To provide security
around queries like that, the pulgin is modfied to support addtional
kibana configuration. Configuration is as follows. 

PUT /securityconfiguration/actionpathfilter/kibana
{
             "rules": [
                {
                    "index" : "testindex1",
                    "types" : [ "testtype1", "testtype5", "testtype13",
"testtype7"]
                },
                {
                    "index" : "testindex2",
                    "types" : [ "testtype19", "testtype21" ]
                },
                {
                    "index" : "testdata",
                    "types" : [ ""testtype1", "testtype2" ]
                }
	     ]
}

This configuration allows users to specify which types in a given index
are accessible by users. 


In 'TomcatHttpServerRestRequest' class, removed final on 'content'
variable. This is done to enable the ES request modification on the fly
so that kibana security can be applied.

In 'SecurityService' class added getKibanaTypes method to obtain the
types that are accessible in a given index. 

In 'ActionPathFilter' class added 'massageKibanaRequest' method to add
'types' filters to Kibana requests. Kibana 3.0.0 uses one index at a
time. So the methtod supports one index at a time. In this method, for
all the types are evaluated against core plugins access permissions. If
the permission evaluation for the type return true, then that type is
added as a filter to narrow down the search query.