Merge branch '6.x'

.travis.yml

README.md

composer.json

src/Aggregation/AbstractAggregation.php

src/Aggregation/Bucketing/AdjacencyMatrixAggregation.php

src/Aggregation/Bucketing/AutoDateHistogramAggregation.php

src/Aggregation/Bucketing/CompositeAggregation.php

src/Aggregation/Bucketing/DateHistogramAggregation.php

src/Aggregation/Bucketing/DateRangeAggregation.php

src/Aggregation/Bucketing/GeoDistanceAggregation.php

src/Aggregation/Bucketing/Ipv4RangeAggregation.php

src/Aggregation/Bucketing/RangeAggregation.php

src/Aggregation/Bucketing/SignificantTextAggregation.php

src/Aggregation/Pipeline/AbstractPipelineAggregation.php

src/Aggregation/Pipeline/BucketSortAggregation.php

src/Aggregation/Pipeline/MovingFunctionAggregation.php

src/Query/Compound/BoolQuery.php

src/Query/Joining/ParentIdQuery.php

src/Query/Span/FieldMaskingSpanQuery.php

src/Search.php