[CAUSEWAY-1554] Prevent double click on buttons (which can cause applications to throw an error, eg concurrency exception)

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.13.1
• Fix Version/s: 1.13.2
• Component/s: Viewer Wicket
• Assignee: Daniel Keir Haywood
• Reporter: Daniel Keir Haywood
• Created: 10/Dec/16 07:42
• Updated: 14/Dec/16 08:10
• Resolved: 10/Dec/16 12:54