Do not offer to submit the exercise to server if deadline has passed

Author: Redande

tmc-plugin/src/fi/helsinki/cs/tmc/data/ResultCollector.java

@@ -109,6 +109,9 @@ public void setReturnable(final boolean returnable) {
     }
 
     private boolean isSubmittable() {
+        if (exercise.hasDeadlinePassed()) {
+            return false;
+        }
 
         for (TestResult result : testCaseResults) {
             if (!result.isSuccessful()) {

tmc-plugin/src/fi/helsinki/cs/tmc/ui/TestResultWindow.java

@@ -149,6 +149,8 @@ public Void apply(final Boolean yes) {
                     return null;
                 }
             });
+        } else if (exercise.hasDeadlinePassed()) {
+            dialogDisplayer.displayMessage("All tests passed, but exercise's deadline has expired.");
         }
     }