* Add some new expression functions and macros.
See misc/math-expr.md for the list of added functions, except for
"like", which previously existed but was not documented.
* Add easymock to datasketches tests.
* Add easymock to distinctcount tests.
* Add easymock to virtual-columns tests.
* Code review comments.
* Clean up code a bit.
* Add easymock to scan-query tests.
* Rework ExprMacros that have multiple impls.
* Improve test coverage.
* Require Java 8 and include some Java 8 dependencies.
- Upgrade Jetty to 9.3.16.v20170120.
- Upgrade DataSketches to 0.8.4.
- Bundle caffeine-cache by default.
- Still target Java 7 when compiling base Druid classes.
* Update cluster, quickstart docs.
* Remove oraclejdk7 from travis.yml.
Roman Leventov
Gian Merlino
Alexander Saydakov
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