[TOP][COMPILER] sum, min, max, transpose, fix dense (#28)

nnvm/python/nnvm/frontend/mxnet.py

nnvm/python/nnvm/top/__init__.py

nnvm/python/nnvm/top/attr_dict.py

nnvm/python/nnvm/top/nn.py

nnvm/python/nnvm/top/reduction.py

nnvm/python/nnvm/top/tensor.py

nnvm/python/nnvm/top/transform.py

nnvm/tests/python/compiler/test_op_fusion.py

nnvm/tests/python/compiler/test_top_level1.py

nnvm/tests/python/compiler/test_top_level4.py