Prevents non numeric characters from entering the input tag in html, except the dot character that serves as decimal seperator
usage examples:
<input type="text" only-num />
<input type="text" ng-model="firstName" only-num />
before using the directive import it to your module
var app = angular.module('myAngularApp',['vitoys'])
app.controller('myController',function($scope){
$scope.firstName = "Scully";
})