[TFLite] Support TFLite FP32 Relay frontend. (#2365)

* Support TFLite FP32 Relay frontend.

* Fix lint issue

* Remove unnecessary variables and packages

* Add method doc string

* Fix capital letter of method doc string

* Add TFLite FP32 Relay frontend based on latest code

* Merge the latest code

* Solve cython issue with relay type inference

* Modify code based on suggestions

python/tvm/relay/frontend/__init__.py

@@ -10,3 +10,4 @@ from __future__ import absolute_import
 from .mxnet import from_mxnet
 from .keras import from_keras
 from .onnx import from_onnx
+from .tflite import from_tflite

tests/scripts/task_python_frontend.sh

@@ -38,3 +38,6 @@ python3 -m nose -v tests/python/frontend/onnx || exit -1
 
 echo "Running nnvm to relay frontend test..."
 python3 -m nose -v tests/python/frontend/nnvm_to_relay || exit -1
+
+echo "Running relay TFLite frontend test..."
+python3 -m nose -v tests/python/frontend/tflite || exit -1