Add pure-java Snappy implementation

[xerial]

Add a pure-java Snappy implementation based on aircompressor: https://github.com/airlift/aircompressor/tree/master/src/main/java/io/airlift/compress/snappy

[maropu]

The SnappyApi abstraction looks fine, but do we need to copy the airlift implementation into our codebase? Any reason not to add the dependency then write delegation code for it in PureJavaSnappy?

[xerial]

aircompressor adds extra dependencies to hadoop ecosystem, guava, etc. Most of them looks like just test/provided dependencies, but porting code would be easier to maintain for us as snappy algorithm will not be changed so much.

And also aircompressor has snappy-java dependency that creates circular dependency ...

[xerial]

Rather, aircompressor will be in trouble if we reference their jar. It will put new and old class files of aircompressor in their classpath.