Don't dismiss issue reporter when email is cancelled

Closes #191

Tusker/Screens/Crash Reporter/IssueReporterViewController.swift

@@ -154,7 +154,11 @@ class IssueReporterViewController: UIViewController {
 extension IssueReporterViewController: MFMailComposeViewControllerDelegate {
     func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
         controller.dismiss(animated: true) {
-            self.dismiss()
+            if result == .cancelled {
+                // don't dismiss ourself, to allowe the user to send the report a different way
+            } else {
+                self.dismiss()
+            }
         }
     }
 }