Docker hotfix (#162)

* added Dockerfile

* intructions for installation with docker

* INSTALL.md: added note to inform nvidia-docker only works with Linux

* dockerfile nccl2 hotfix

* INSTALL.md update

* removes explicit install of NCCL2 as it is included in the CUDA image

INSTALL.md

@@ -56,12 +56,12 @@ python setup.py build develop
 # MACOSX_DEPLOYMENT_TARGET=10.9 CC=clang CXX=clang++ python setup.py build develop
 ```
 
-### Option 2: Docker Image (Requires CUDA, Linux Only)
+### Option 2: Docker Image (Requires CUDA, Linux only)
 
-Build image with defaults (`CUDA_VERSION=9.0`, `CUDNN_VERSION=7`):
+Build image with defaults (`CUDA=9.0`, `CUDNN=7`):
 
     nvidia-docker build -t maskrcnn-benchmark docker/
     
 Build image with other CUDA and CUDNN versions:
 
-    nvidia-docker build -t --build-arg CUDA_VERSION=9.2 --build-arg CUDNN_VERSION=7 maskrcnn-benchmark docker/ 
+    nvidia-docker build -t --build-arg CUDA=9.2 --build-arg CUDNN=7 maskrcnn-benchmark docker/ 

docker/Dockerfile

-ARG CUDA_VERSION=9.0
-ARG CUDNN_VERSION=7
+ARG CUDA="9.0"
+ARG CUDNN="7"
 
-FROM nvidia/cuda:${CUDA_VERSION}-cudnn${CUDNN_VERSION}-devel-ubuntu16.04
+FROM nvidia/cuda:${CUDA}-cudnn${CUDNN}-devel-ubuntu16.04
 
 # install basics
 RUN apt-get update -y \
- && apt-get install -y git curl ca-certificates bzip2 cmake tree htop bmon iotop g++ \
- && apt-get install -y --no-install-recommends libnccl2=2.3.5-2+cuda${CUDA_VERSION}
+ && apt-get install -y git curl ca-certificates bzip2 cmake tree htop bmon iotop g++
 
 # Install Miniconda
 RUN curl -so /miniconda.sh https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh \