use elephantbird HadoopCompat to get running on hadoop 2 mr1

This adds support for hadoop 2 while maintaining support for 1.x

One thing to note though: It breaks some of the example configs that do things like this:
```
kafka.fetch.buffer.size=
```

when a key that is expected to be parsed as an integer is uncommented in the properties file but not set, hadoop 2 will set this as empty string, where hadoop 1.x set it as null. hadoop 2 will through an exception when it tries to parse the empty string as an int. 

leaving keys intented to be set using default as commented out works in both cases (and I think is more idiomatic in general).

```
# kafka.fetch.buffer.size=
```