angular validator improvements

Hello,

There are couple of changes in my fork:
- validate only after submit form;
- improve validator to work with dynamic form;
- introduce angularValidatorProvider to decorate angular form and ng-model to work with dynamic name;
- add validator-group and validator-group-elements options (if "validator-group" option is defined then 'has-error' class was also set to this element and if 'validator-group-elements' was defined then group will be invalid if one of the group elements is invalid);
- introduce 'validator-message-append-to' option to define place where error message was appended;

If you are interested in any of this changes, then review and merge it into your branch :)