AbstractResultsIterator::current() returns null if no documents are found
fixed a bug that ignored the zero value to the min_doc_count option
added nested aggregation
added nested_aggregation unit test
Range aggregations test fix
Connection remove mapping test case
Merge pull request #57 from linasmo/mapping_update_test

Connection remove mapping test case
Merge pull request #55 from ivannis/nested_aggregation

added nested aggregation
Merge pull request #52 from martiis/issue_51

AbstractResultsIterator::current() returns null if no documents are found
added functional test to TermsAggregation with zero min_doc_count
Merge pull request #54 from ivannis/master

fixed a bug that ignored the zero value to the min_doc_count option