Add support for NodesHotThreads

Closes #508.
Smarter format recognition when parsing nodes.hot_threads response
Bulk-operation without index/type

Bulk-operations is not working if elasticsearch settings
rest.action.multi.allow_explicit_index
re #880 - Ensures that a nested filter consisting of only a filter does not result in a conditionless NEST filter (leading to its exclusion from generated json query)
Update tests for bulk-update with FixedPath to work if even if the _index attribute not are allowed
Update tests for multiperculate with FixedPath to work if even if the _index attribute not are allowed
Update tests for multisearch with FixedPath to work if even if the _index attribute not are allowed
Update tests forMultiSearch with FixedPath to work if even if the index attribute not are allowed
Update serializer for Bulk, MultiSearch and MultiPercolate to ignore index-parameter if that is the same as FixedPath
Correcting BulkIndexDetailsFixedPath test
Add method to check if empty collections should be included in result serialized json result
Update documentation
Update descriptor's with Fields()/Path()
Update mappings to allow inheritance for multifieldmap
Add multifieldmap also the GenericMapping
Change mapping to use contructor for default type
Fix full mapping test

If store and enable are the same values as the server are configured as
the items are not returned back as response when get-mapping are
executed.
Test has wrong base class
Test-issie is still not solved in ES
Merge pull request #886 from Tasteful/fix/failing-tests

Fixing tests that are failing in some environments