add setup and README for deployment

deploy/README.md

+### Installation
+The setup of the decoder for deployment depends on the source code of [kenlm](https://github.com/kpu/kenlm/), first clone it to current directory (i.e., `deep_speech_2/deploy`)
+
+```shell
+git clone https://github.com/kpu/kenlm.git
+```
+
+Then run the setup
+
+```shell
+sh setup.sh
+```
+
+After the installation succeeds, go back to the parent directory
+
+```
+cd ..
+```
+
+### Deployment
+
+For GPU deployment
+
+```
+CUDA_VISIBLE_DEVICES=0 python deploy.py
+```
+
+For CPU deployment
+
+```
+python deploy.py --use_gpu=False
+```
+
+More help for arguments
+
+```
+python deploy.py --help
+```

deploy/setup.sh

+echo "Run decoder setup ..."
+
+python decoder_setup.py install
+rm -r ./build
+
+echo "\nRun scorer setup ..."
+
+python scorer_setup.py install
+rm -r ./build
+
+echo "\nFinish the installation of decoder and scorer."