Improve displaying of validation message

The validation message must be improved to enable some features that were frequently asked:

• Different position in DOM of the validation message / message template
• Enable validation message / message template animation when observable transitions from valid to invalid state and viceversa
• Enable different ways of showing the validation message (data-xxx attributes, custom methods - eg. QTip, toasts etc.)

If more improvements should be made, leave a comment and I'll update the list.

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Related issues: #260 Showing validation message on popup #238 Qtip with Knockout-Validation #348 Custom position to messageTemplate #410 Custom method to display error message #456 Placing custom validation template #432 Allow alternative means of hiding/showing error message. #302 Error messages from data-val-xxx attributes