tech(build): slimdown the size of the build container

scripts/build/Dockerfile

 FROM centos:6.6
 
-RUN yum install -y yum-plugin-ovl initscripts curl tar gcc libc6-dev git gcc-c++ openssl-devel \
-    yum install -y g++ make automake autoconf curl-devel zlib-devel httpd-devel apr-devel apr-util-devel sqlite-devel \
-    yum install -y wget yum-utils bzip2 bzip2-devel \
-    yum install -y fontconfig freetype freetype-devel fontconfig-devel libstdc++ \
-    yum install -y rpm-build patch readline readline-devel libtool bison lzma \
+RUN yum install -y yum-plugin-ovl initscripts curl tar gcc libc6-dev git gcc-c++ openssl-devel && \
+    yum install -y g++ make automake autoconf curl-devel zlib-devel httpd-devel apr-devel apr-util-devel sqlite-devel && \
+    yum install -y wget yum-utils bzip2 bzip2-devel && \
+    yum install -y fontconfig freetype freetype-devel fontconfig-devel libstdc++ && \
+    yum install -y rpm-build patch readline readline-devel libtool bison lzma && \
     yum install -y which tar
 
 # Install RUBY 1.9.3
 # install necessary utilities
 # RUN yum install -y which tar
-RUN gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
-RUN curl -sSl https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer | bash -s stable
-RUN source /etc/profile.d/rvm.sh
-RUN /bin/bash -l -c "rvm requirements"
-RUN /bin/bash -l -c "rvm install 2.1.9"
-RUN /bin/bash -l -c "rvm use 2.1.9 --default"
+RUN gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 && \
+    curl -sSl https://raw.githubusercontent.com/rvm/rvm/master/binscripts/rvm-installer | bash -s stable && \
+    source /etc/profile.d/rvm.sh && \
+    /bin/bash -l -c "rvm requirements" && \
+    /bin/bash -l -c "rvm install 2.1.9" && \
+    /bin/bash -l -c "rvm use 2.1.9 --default"
 
 # install nodejs
-RUN curl --silent --location https://rpm.nodesource.com/setup_6.x | bash -
-RUN yum install -y nodejs --nogpgcheck
+RUN curl --silent --location https://rpm.nodesource.com/setup_6.x | bash - && \
+    yum install -y nodejs --nogpgcheck
 
-RUN wget https://dl.yarnpkg.com/rpm/yarn.repo -O /etc/yum.repos.d/yarn.repo
-RUN yum install -y yarn --nogpgcheck
+RUN wget https://dl.yarnpkg.com/rpm/yarn.repo -O /etc/yum.repos.d/yarn.repo && \
+    yum install -y yarn --nogpgcheck && \
+    wget https://storage.googleapis.com/golang/go1.7.4.linux-amd64.tar.gz && \
+    tar -C /usr/local -xzf go1.7.4.linux-amd64.tar.gz
 
 ENV GOLANG_VERSION 1.7.4
-
-RUN wget https://storage.googleapis.com/golang/go1.7.4.linux-amd64.tar.gz
-RUN tar -C /usr/local -xzf go1.7.4.linux-amd64.tar.gz
-
 ENV PATH /usr/local/go/bin:$PATH
 
 RUN mkdir -p /go/src /go/bin && chmod -R 777 /go