With this change, any call to `find`, `all`, etc where the first argument is a Symbol, will assume that that Symbol is the name of the selector. This makes the `match` option on the `id` selector impossible, so `find(:foo)` will no longer find elements by id.
This change is in preparation for allowing selectors without locators, as discussed in #783, which we will probably hold off with until Capybara 2.1, because it is too much work.
This commit ensures we won't have to break the API to make implementing #783 possible.
