Add spec for wait methods

This is a migration of the watir-webdriver wait_spec with the following changes:

1. The error message checking in the Watir.default_time specs was removed. The error messages are already checked in the specs for the specific wait methods.
2. Added deviations for watir-classic on error messages that include element locators. Watir-classic currently includes :tag_name as an array rather than a string.