normalize persist terms

nodejs.json

@@ -12,11 +12,11 @@
             "hash": "2888f2303bcaa35f05b3dce7cbfee58af77dcea6bed4b9ff549b181c65eb4565"
         }
     },
-    "env_add_path": ["nodejs", "$data_dir"],
+    "env_add_path": ["nodejs", "$persist_dir"],
     "persist": "nodejs/node_modules",
     "post_install": "
-# Set npm prefix to install module inside $data_dir
-Set-Content -Value \"prefix=$data_dir\" -Path $data_dir\\node_modules\\npm\\npmrc
+# Set npm prefix to install module inside $persist_dir
+Set-Content -Value \"prefix=$persist_dir\" -Path $persist_dir\\node_modules\\npm\\npmrc
 npm update -g",
     "checkver": {
         "url": "https://nodejs.org/en/download/current/",

php.json

@@ -29,7 +29,7 @@
         "php-cgi.exe"
     ],
     "env_set": {
-        "PHP_INI_SCAN_DIR": "$data_dir\\conf"
+        "PHP_INI_SCAN_DIR": "$persist_dir\\conf"
     },
     "post_install": "
 #Copy PHP configuration file to expected location

ruby.json

@@ -26,10 +26,10 @@
         }
     },
     "extract_to": [ "", "devkit" ],
-    "env_add_path": ["bin", "$data_dir\\gem\\bin"],
+    "env_add_path": ["bin", "$persist_dir\\gem\\bin"],
     "env_set": {
-        "GEM_HOME": "$data_dir\\gem",
-        "GEM_PATH": "$data_dir\\gem"
+        "GEM_HOME": "$persist_dir\\gem",
+        "GEM_PATH": "$persist_dir\\gem"
     },
     "post_install": "pushd $dir\\devkit;echo \"---`n- $dir\" | out-file config.yml -enc default; ruby dk.rb install;popd;",
     "checkver": {