* Adds Validate class in util with accompanying regular expressions
* Provides tests for NotificationEmail and Validate.EmailAddress
* Provides default values for NotificationEmail Subject and Message
These default values resolve the underlying issue of #3021 w/out
needing to modify external sources (such as impl of IMessagingHandler)
* Moves _liveMode check into Allow method for stream-lined Email/Sms/Web
* Updates default _resetTime to default(DateTime) to make explicit the first
invocation semantics
* Updates _resetTime increment to be hourly instead of rounded hours as this
caused strange behavior in the units tests when too close to the hour
* Synchronizes Allow method to avoid potential race conditions with += on
_count and setting of the _resetTime
Martin Molinero