Data Load from Asterix

Ideally, we can use an object pool to reuse edge values, like here:
https://github.com/pregelix/pregelix/blob/master/pregelix-example/src/main/java/edu/uci/ics/pregelix/example/inputformat/TextPageRankInputFormat.java

But here since we need to have a pool for each edge type, it is harder.  It would be nice to add a TODO item here.