mostly finished aggregation docs, one section missing
Fixed too long source lines
Fixed too long source lines
Added a few more Java 6 and 7 examples
Added SQL like describtion of the different available aggregations
Added a short sentence for different aggregations
Fixed titles of different aggregations
Added an example chapter
fixed anchors
Added implementing aggregations chapter
Merge pull request #2840 from noctarius/aggregators-docs

Aggregators docs