Update TVM Version and CI scripts (#46)

vta/tests/scripts/task_python_test.sh

 #!/bin/bash
 
-export PYTHONPATH=python:nnvm/python:nnvm/tvm/python:nnvm/tvm/topi/python
+export PYTHONPATH=python:tvm/nnvm/python:tvm/python:tvm/topi/python
 
 echo "Running unittest..."
 python -m nose -v tests/python/unittest || exit -1