FORM VALIDTION
this.userform = this._formbuilder.group({
  first_name: [this.user.first_name, Validators.required],
  last_name: ['', Validators.required],
  username: ['', Validators.compose(
    [
      Validators.required,Validators.minLength(5)
    ]
  )],
  password: ['',Validators.compose([
    Validators.required,ValidationService.passwordValidator
  ])],
  email: ['', Validators.compose([
    Validators.required,ValidationService.emailValidator
  ])],
  role: ['', Validators.required],

})

constructor(private _http:Http){}

 static passwordValidator(control) {
  if(control.value != undefined){
  if (!control.value.match(/^(?=.*[0-9])[a-zA-Z0-9!@#$%^&*]{6,100}$/)) {
    return { 'invalidPassword': true };
  }
 }

 }

static emailValidator(){

return this._http. //this returns an error i would like to
      //query server to see if email exists

 }