TestHistogram zipfan dataset as well the interfaces of the sort based…

[lmd1993]

… joins

The parallel sort related elements, mainly includes:

1. parallel sort running frameworks including the histograms, histogrammerge, forward operators.
2. two types of histogram and their inner algorithms covering streaming based numeric histogram and ternary based string histogram.
3. provides fours samplers, bernoulli, reservoir, random and chain for further optimizations.
4. Some testSet and testCodes. Further works: Split the types of implementations separately into two sub-branches to accommodate the basic types of parallel sort.
5. Running framework as well as the numeric type.
6. Extend the framework onto the string case. Make the inner structures according to the normal rules of hyracks. Change-Id: I8eb7f0dddcd4b754b1cbe273ef8db5be966654d5