Caching recent searches for autocomplete

Added new panel at autocomplete with recent searches, minlength for
autocomplete changed to 0, but will do request to database only if 2+
chars in string. also did little changes at jquery.tagsinput
Yes, exactly. So why did you change it? I only want it to check if `restrict_to` was sent to the function. Checking `if not restrict_to` doesn't mean the same as `if not restrict_to?`.

Let's say we have a function like this, "Multiply the two numbers given. If only one is given, return it"
````
multi = (x, y) ->
  if y?
    x * y
  else
    x
````
Using your method we'd get `multi(10, 0) == 10` when we expected `multi(10, 0) == 0`