Add LZF safe encoder in LZFCompressor

Selecting the safe encoder fixes a 64bit JVM crash on big-endian architectures with
LZF UnsafeChunkEncoderBE.

Example of such a big-endian architecture is Solaris SPARC 64bit (another one is POWER).

Without safe encoder, LZF uses the unsafe encoder, and crashes when
for example this command is executed

        PUT /_template/logstash
        {
                "template" : "logstash-*",
                "settings" : {
                        "index.refresh_interval" : "5s"
                },
                "mappings" : {
                        "_default_" : {
                                "_all" : { "enabled" : true },
                                "dynamic_templates" : [ {
                                        "string_fields" : {
                                                "match" : "*",
                                                "match_mapping_type" : "string",
                                                "mapping" : {
                                                        "type" : "string",
                                                        "index" : "analyzed",
                                                        "omit_norms" : true,
                                                        "fields" : {
                                                                "raw" : {
                                                                        "type": "string",
                                                                        "index" : "not_analyzed",
                                                                        "ignore_above" : 256
                                                                }
                                                        }
                                                }
                                        }
                                } ],
                                "properties" : {
                                        "@version": { "type": "string", "index": "not_analyzed" },
                                        "geoip"  : {
                                                "type" : "object",
                                                "dynamic": true,
                                                "path": "full",
                                                "properties" : {
                                                        "location" : { "type" : "geo_point" }
                                                }
                                        }
                                }
                        }
                }
        }

A crash file is available at https://gist.github.com/jprante/79f4b4c0b9fd83eb1c9b