Adding Keras frontend and sources

hpvm/projects/keras/README.md

hpvm/projects/keras/cmake_template/CMakeLists.txt

hpvm/projects/keras/frontend/approxhpvm_translator.py

hpvm/projects/keras/frontend/config.py

hpvm/projects/keras/frontend/hpvm_dfg_translator.py

hpvm/projects/keras/frontend/hpvm_intrinsics.py

hpvm/projects/keras/frontend/weight_utils.py

hpvm/projects/keras/keras_environment.yml

hpvm/projects/keras/legacy/generated/vgg16/approxhpvm_src.cc

hpvm/projects/keras/legacy/generated/vgg16/src.cc

hpvm/projects/keras/legacy/keras_environment.yml

hpvm/projects/keras/legacy/keras_environment_deps.yml

hpvm/projects/keras/setup.py

hpvm/projects/keras/src/Benchmark.py

hpvm/projects/keras/src/__init__.py

hpvm/projects/keras/src/alexnet.py

hpvm/projects/keras/src/alexnet2.py

hpvm/projects/keras/src/alexnet_imagenet.py

hpvm/projects/keras/src/legacy/lenet_conv_test.py

hpvm/projects/keras/src/legacy/mobilenet_imagenet.py