Change made for TezClient, DAG, Vertex, Edge, EdgeProperty, UserPayload and a couple other classes.
Haven't changed EntityDescriptors etc - since I don't think those are critical.
Also adds Javadoc for some missing methods in Edge, UserPayload.
bikassaha - review please.
bikassaha do you intend to use builder to create the DAG here ?
Today I found one issue of DAG that the verify method could not been called multiple times https://issues.apache.org/jira/browse/TEZ-1247
I think it would be better to use builder here, any thoughts ?