support batch for regionproposal (#2928)
support batch for regionproposal (#2928)

* support batch for regionproposal

intel-analytics/BigDL,intel-analytics/BigDL,yangw1234/BigDL,yangw1234/BigDL,yangw1234/BigDL,intel-analytics/BigDL,yangw1234/BigDL,intel-analytics/BigDL