Do not assume process, so the module can be loaded into plv8

lib/sequelize.js

@@ -5,7 +5,7 @@ var Utils             = require("./utils")
   , Migrator          = require("./migrator")
   , QueryInterface    = require("./query-interface")
 
-if (parseFloat(process.version.replace('v', '')) < 0.6) {
+if (typeof process != 'undefined' && parseFloat(process.version.replace('v', '')) < 0.6) {
   console.log("DEPRECATION WARNING: Support for Node.JS < v0.6 will be canceled in the next minor release.")
 }