Merge branch 'centos6' into 'master'

Some installation fixes for Centos 6

See merge request !260

doc/prepare.md

@@ -112,10 +112,13 @@ Please read [the prerequisites for all platforms](#prerequisites-for-all-platfor
 This is tested on CentOS 6.5:
 ```
-sudo yum install http://yum.postgresql.org/9.3/redhat/rhel-6-x86_64/pgdg-redhat93-9.3-1.noarch.rpm
+sudo yum install http://yum.postgresql.org/9.5/redhat/rhel-7-x86_64/pgdg-redhat95-9.5-2.noarch.rpm
 sudo yum install https://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
-sudo yum install postgresql93-server libicu-devel cmake gcc-c++ redis ed fontconfig freetype libfreetype.so.6 libfontconfig.so.1 libstdc++.so.6 golang nodejs
+sudo yum install postgresql95-server postgresql95-devel libicu-devel cmake gcc-c++ redis ed fontconfig freetype libfreetype.so.6 libfontconfig.so.1 libstdc++.so.6 golang nodejs npm
+sudo npm install phantomjs-prebuilt@2.1.12 -g
+
+bundle config build.pg --with-pg-config=/usr/pgsql-9.5/bin/pg_config
 sudo rvm install 2.3
 sudo rvm use 2.3
 #Ensure your user is in rvm group