Single quotes in username are bad

[magicalbob]

Adding a user with a single quote in username is accepted by graylog2-web-interface, but you can't log in with that user and you can't delete the user.

Add

        if (username.indexOf("'") > -1 ) {
          validationFailure( createUsernameField, "Username can't have quotes.");
          domElement.setCustomValidity('Username cannot have quotes.');
        } else {
          $.ajax({

.
.
.

          });
        }

to app/assets/javascripts/main.js stops anyone from doing something stupid like putting a single quote in a username.

I'm a newb and haven't worked out how to commit changes .......