Fixed docker builds label and space

Author: cypof

docker/cpu/Dockerfile

@@ -1,5 +1,5 @@
 FROM ubuntu:16.04
-MAINTAINER [email protected]
+LABEL maintainer [email protected]
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
         build-essential \

docker/gpu/Dockerfile

@@ -1,5 +1,5 @@
 FROM nvidia/cuda:8.0-cudnn5-devel-ubuntu16.04
-MAINTAINER [email protected]
+LABEL maintainer [email protected]
 
 RUN apt-get update && apt-get install -y --no-install-recommends \
         build-essential \
@@ -33,7 +33,7 @@ ENV CLONE_TAG=1.0.0-rc4
 RUN git clone -b ${CLONE_TAG} --depth 1 https://github.com/BVLC/caffe.git . && \
     pip install --upgrade pip && \
     cd python && for req in $(cat requirements.txt) pydot; do pip install $req; done && cd .. && \
-    git clone https://github.com/NVIDIA/nccl.git && cd nccl && make -j install && cd .. && \
+    git clone https://github.com/NVIDIA/nccl.git && cd nccl && make -j install && cd .. && rm -rf nccl && \
     mkdir build && cd build && \
     cmake -DUSE_CUDNN=1 -DUSE_NCCL=1 .. && \
     make -j"$(nproc)"