This is most likely a false positive, I am a web developer and have been using Telerik products for years, there is no way that they contain trojans. Telerik provide professional class developer tools for web (and other) applications.
Also, it seems like Avast only has this false positive in Firefox. I have been checking my production websites in Chrome and IE8+, no trojans detected.
PLEASE AVAST PROVIDE QUICK UPDATE before our customers start complaining. Telerik products are WIDELY used in web development and having a false positive in such a context is not a good thing AT ALL.