Check bundler version to avoid error with unsupported command line arguments

plugins/bundler/bundler.plugin.zsh

@@ -4,6 +4,8 @@ alias bp="bundle package"
 alias bo="bundle open"
 alias bu="bundle update"
 
+bundler_version=`bundle version | cut -d' ' -f3`
+if [[ $bundler_version > '1.4.0' || $bundler_version = '1.4.0' ]]; then
   if [[ "$(uname)" == 'Darwin' ]]
   then
     local cores_num="$(sysctl hw.ncpu | awk '{print $2}')"
@@ -11,6 +13,9 @@ else
     local cores_num="$(nproc)"
   fi
   eval "alias bi='bundle install --jobs=$cores_num'"
+else
+  alias bi='bundle install' 
+fi
 
 # The following is based on https://github.com/gma/bundler-exec