Provide message describing book search parameters

I know we're not localizing yet. But this sort of code will make things particularly difficult when we do. If JavaScript has something like C#'s string.Format() or C++ printf, using that to allow various items to be inserted into a string at places specified in the string is much easier to localize. Not easy to do at the complexity of this message, though...you might need a few templates inside templates. I'm not sure it's worth the effort to change at this stage...let's wait and see whether we do localize...just something to bear in mind.

(For example, consider how the code, not just the strings, has to be changed if a particular language forces a word order like "Searching for books in English containing "animals" on the shelf Featured, none were found")