Wbiesing/readheadset uses static configuration

@anbangx @JavierJia 

We can't rely on any transient member variables staying intact since all classes are created via reflection and `newInstance`.  As a result, the `forceReadEntireBody` and `write*` changes were being lost.

This PR changes those values in two ways: 

- puts the `readEntireBody` flag into the `readFields` stream rather than some configuration.  Otherwise, it's impossible to know how the *previous* `write` stored the ReadHeadSet.
- makes the `writeEntireBody` a static configuration parameter which is now set inside of the BUILD_HYRACKS code and in the pregelix vertex input and output format adapters.