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.
I looked into 60ed5145 and discovered that Capybara::Query#initialize escapes
options[:text]. I think this is a bit confusing, and it messes up the error
message, so options[:text] is now escaped on the fly in matches_filters?.
Also add tests with blanks in them just to be on the safe side.
