Fix installation instructions and pin PyTorch to a nightly (#557)

INSTALL.md

 ## Installation
 
 ### Requirements:
-- PyTorch 1.0 from a nightly release. Installation instructions can be found in https://pytorch.org/get-started/locally/
+- PyTorch 1.0 from a nightly release. It **will not** work with 1.0 nor 1.0.1. Installation instructions can be found in https://pytorch.org/get-started/locally/
 - torchvision from master
 - cocoapi
 - yacs
@@ -23,8 +23,14 @@ conda activate maskrcnn_benchmark
 # this installs the right pip and dependencies for the fresh python
 conda install ipython
 
-export INSTALL_DIR=$PWD
+# maskrcnn_benchmark and coco api dependencies
+pip install ninja yacs cython matplotlib tqdm
+
+# follow PyTorch installation in https://pytorch.org/get-started/locally/
+# we give the instructions for CUDA 9.0
+conda install -c pytorch pytorch-nightly torchvision cudatoolkit=9.0
 
+export INSTALL_DIR=$PWD
 
 # install pycocotools
 cd $INSTALL_DIR
@@ -37,13 +43,6 @@ cd $INSTALL_DIR
 git clone https://github.com/facebookresearch/maskrcnn-benchmark.git
 cd maskrcnn-benchmark
 
-# maskrcnn_benchmark and coco api dependencies
-pip install -r requirements.txt
-
-# follow PyTorch installation in https://pytorch.org/get-started/locally/
-# we give the instructions for CUDA 9.0
-conda install -c pytorch pytorch torchvision cudatoolkit=9.0
-
 # the following will install the lib with
 # symbolic links, so that you can modify
 # the files if you want and won't need to