Add optional regexp validation to service dialogs

Text boxes now expose a drop-down for validator type and
a text field for validator rule. When 'Regular Expression'
is selected for the validator type, user input will be
matched against the provided validator rule. This is similar
to how Foreman validates user input for Smart Variables.

https://bugzilla.redhat.com/show_bug.cgi?id=1085158
Are you talking about reg-ex modifiers like "i" for case-insensitive?  I can make it so that you can specify either just the pattern (like the current format) or the full "/pattern/modifiers" format.  I just implemented the same feature-set as is currently available in the Foreman project, hence the limitation to just the pattern.  Thoughts?