Not all '<' and '>' are stripped from the search query

The characters '<' or '>' are stripped from the search keyword before a search is done, to prevent the XSS filter from returning a 400 page. However, only the first occurence of '<' and '>' is replaced, so you still get a 400 page is the search keywords contain more than one < or >.

Steps to reproduce:
1. open the GoGreen site
2. search for "<h1>bla</h1>" (without quotes)

Expected: a search is done for "h1bla/h1"
Actual: a 400 page is shown