Description of problem:
 Retry and Cancel dialogs do not support 'confirmation by Enter'

Version-Release number of selected component (if applicable):
 ipa-server-3.3.3-6.el7.x86_64
 browser version: FirefoxESR 24.2.0 and Firefox 26.0

How reproducible:
 100%

Steps to Reproduce:
1.Login as admin user
2.Navigate to User page
3. Click on "Add "
4.Add a user called "testuser"
5.Click on "Add" again
6.Add the same user again (tseruser)
7.We will get a error message "user already available"
8.Focus "Cancel" button on error dialog with "Tab" key
9.Press "Enter" key.

Actual results:
 Error dialog does not go off.

Expected results:
 Error dialog should be closed

Additional info:
 If we use space bar error dialog goes off.