Changes

[https://webmademovies.lighthouseapp.com/projects/65733/tickets/458-protect-from-invalid-times-in-trackevents Bug 458]<br/>

[https://webmademovies.lighthouseapp.com/projects/65733-butter/tickets/459-fix-the-error-message-given-for-invalid-start-and-end-times-for-track-events Bug 459]<br/>

[https://webmademovies.lighthouseapp.com/projects/65733-butter/tickets/493-if-a-track-event-is-double-clicked-and-the-editor-is-already-opened-focus-the-editor Bug 493]<br/>