Added a run once flag

Added a 'run once' node to the config, which informs the library that
the test should only be run once, immediately. This is primarily for the
sake of testing tests.
Cleanup, bug fix, enhancement

Removed a number of commented-out code that was no longer applicable.

Fixed the email message header and subject.

Added a run-once flag and an element text verification method.
Attribute verification

Added code to verify an IWebElement attribute's value
Bug fix: return to site URL at end of each case
Action and Verify enhancements

Action and Verification classes have been enhanced for greater
flexibility and easier human-reading in the config.
Error Message overhaul part 1

Drastically changed how test failures are reported to improve
intelligibility of information and flexibility of error reporting.
Error Message overhaul part 2

Wrapping up changes to enhance error message reporting
Error Message overhaul part 3

Cleanup, bug fixes.