[TECHNICAL-SUPPORT] LPS-37546 Search Portlet - Multiple searches can be sumitted upon clicking several times on the search icon in the main view

Hi Tamás,

Read the full commit message of the 1st commit and let me know if you've any concerns.
With this change to the util.js, you can see that the search icon is visually (and programmatically) disabled after the 1st submit.

There was a discussion about a similiar issue at http://in.liferay.com/web/global.engineering/forums/-/message_boards/view_message/1207023, where Ray also suggested to use the default submit function. However, that logic uses aui-io (therefore, AJAX), so Vilmos had to find a different approach to fix.

For this current issue, def. function seems enough.

== background
1. When you place Search portlet on page, its main view uses liferay-ui:search taglib >>> The start.jsp of this taglib uses an "image" type <input> to display the search icon, and this icon is supposed to submit the form. Let's call initial search.
2. The main entry point to the result page is the portlet/search/search.jsp. The submit icon is the same, but here we already use the default submit function. If you take a look at the declaration of the aui:form, in the onSubmit action 1st we call "event.preventDefault;" to prevent executing the default submit action of the form. Though, in older versions of IE, it doesn't work, we have to set "event.returnValue = false" to work in a normal form. AFAIK, an aui:form will fire a wrapped event, so it works, but the taglib uses plain HTML form, that's why we use the "return false;" after the "search();" in the onSubmit action of the taglib's form.

Tested on 
- IE7/8/9
- FF 21.0 (For Canonical Ubuntu)
- Google Chrome 28.0.1500.52

Regards,
Tibor