Add missing tests to Pangram.

- ensure titles of tests match those in
  https://github.com/exercism/x-common/blob/master/exercises/pangram/canonical-data.json

exercises/pangram/src/test/java/PangramTest.java

 
 
     @Test
-    public void emptySentence() {
+    public void sentenceEmpty() {
         assertFalse(Pangrams.isPangram(""));
     }
 
     @Ignore
     @Test
-    public void testLowercasePangram() {
+    public void pangramWithOnlyLowerCase() {
         assertTrue(Pangrams.isPangram("the quick brown fox jumps over the lazy dog"));
     }
 
 
     @Ignore
     @Test
-    public void mixedCaseAndPunctuation() {
+    public void anotherMissingCharacterX() {
+        assertFalse(Pangrams.isPangram("the quick brown fish jumps over the lazy dog"));
+    }
+
+    @Ignore
+    @Test
+    public void pangramWithUnderscores() {
+        assertTrue(Pangrams.isPangram("\"the_quick_brown_fox_jumps_over_the_lazy_dog\""));
+    }
+
+    @Ignore
+    @Test
+    public void pangramWithNumbers() {
+        assertTrue(Pangrams.isPangram("\"the 1 quick brown fox jumps over the 2 lazy dogs\""));
+    }
+
+    @Ignore
+    @Test
+    public void missingLettersReplacedByNumbers() {
+        assertFalse(Pangrams.isPangram("\"7h3 qu1ck brown fox jumps ov3r 7h3 lazy dog\""));
+    }
+
+    @Ignore
+    @Test
+    public void pangramWithMixedCaseAndPunctuation() {
         assertTrue(Pangrams.isPangram("\"Five quacking Zephyrs jolt my wax bed.\""));
     }
 
     @Ignore
     @Test
-    public void nonAsciiCharacters() {
+    public void pangramWithNonAsciiCharacters() {
         assertTrue(Pangrams.isPangram("Victor jagt zwölf Boxkämpfer quer über den großen Sylter Deich."));
     }
 
+
+    @Ignore
+    @Test
+    public void panagramInAlphabetOtherThanAscii() {
+        assertFalse(Pangrams.isPangram("Широкая электрификация южных губерний даст мощный толчок подъёму сельского хозяйства."));
+    }
 }