Fix warning by Google Closure compiler

That @ will generate the following warning in Google Closure Compiler:

<pre>
Aug 23, 2013 3:08:27 PM com.google.javascript.jscomp.LoggerErrorManager println
WARNING: /home/rodrigo/.matterhorn/grails-assets/development/static/js/jquery/form/jquery.form.js:1: WARNING - Parse error. Non-JSDoc comment has annotations. Did you mean to start it with '/**'?
/*!
^

Aug 23, 2013 3:08:27 PM com.google.javascript.jscomp.LoggerErrorManager printSummary
WARNING: 0 error(s), 1 warning(s)
</pre>