Fixed several issues with aggregations and bulk indexing.

Fixed

• Aggregations with _aggs in different order
• JSON serialization of Infinite and NaN
• Fixed race condition during bulk indexing

Changed

• BREAKING: Fields in responses renamed and nested differently: + query.hits moved to hits + query.matches_estimated renamed to count + query.total_count renamed to doc_count
• MERGE method is deprecated and will be removed, use UPDATE instead
• Default UUID mode is now encoded + compact