ActiveIf#options related stuff are no longer used

so make its use produce warnings
add caller information in warnings (thanks to sorah)
use interplation instead of String#+ and use caller[0] instead of
caller[1]
use RSpec's #be_* because it's more informative than simple #be
no \b nor /x in regular expressions for maintainability
refactor the spec

* no instance variable; use around() instead
* uses context()
* use should() instead of expect()
* matchs full messages
Merge pull request #34 from gfx/gfx/no-options-for-activeif-new

Make ActiveIf#options related stuff produce warnings