Major plugin improvement following the new 0.90.x version

Changelog:
- unified mapping for all node/way/relation indices (allow user to query one, all or a combination of these indices)
- one-shot insert: ways have their locations at insert time (no more need for SpecializedIndexBuilder)
- take advantage of both `geo_point` and `geo_shape` types using entities' centroid and shape fields
- introduce multi-threading and several basecode improvement to maximize insertion performance
- new parameters to fine-tune the plugin with your hardware
- use latest Osmosis 0.43-RELEASE and elasticsearch 0.90.0.RC2 (eagerly expecting 1.0.0 release :)
- documentation