Merge pull request #36 from fengjingchao/master

Framework: DataRequest implementation
implement bootstrap interface 
implement bootstrap interface 
implement bootstrap interface 
Merge pull request #43 from xiaoyunwu/master

implement bootstrap interface 
first step toward regression test
change Config to map[string]string
add AbortTask to framework interface
change SetEpoch on framework to IncEpoch
reponse to Hongchao's comment
Merge pull request #44 from xiaoyunwu/master

first step toward regression test
refactor the topology interface so that it doesn't expose NumberOfTasks
initial version of regression test, commented out as it will break
hide the implementation details
provide hint on how the start should behave
respond to Hongchao's comments
respond to Hongchao's comments
respond to Hongchao's comments
respond to Hongchao's comments
Merge pull request #47 from xiaoyunwu/master

initial regression test and refactored the topology interface