[MINOR] Update Docker pointers
[MINOR] Update Docker pointers

shimamoto/incubator-predictionio,shimamoto/incubator-predictionio,marevol/incubator-predictionio,dszeto/incubator-predictionio,mars/incubator-predictionio,dszeto/incubator-predictionio,PredictionIO/PredictionIO,dszeto/incubator-predictionio,takezoe/incubator-predictionio,PredictionIO/PredictionIO,marevol/incubator-predictionio,himanshudhami/PredictionIO,mars/incubator-predictionio,mars/incubator-predictionio,takezoe/incubator-predictionio,marevol/incubator-predictionio,himanshudhami/PredictionIO,dszeto/incubator-predictionio,shimamoto/incubator-predictionio,himanshudhami/PredictionIO,takezoe/incubator-predictionio,himanshudhami/PredictionIO,takezoe/incubator-predictionio,marevol/incubator-predictionio,PredictionIO/PredictionIO,shimamoto/incubator-predictionio,mars/incubator-predictionio