Fix #85: add support for a replaceAllEmojis function

Adds a function that replaces all the emojis in a string by another string.

src/main/java/com/vdurmont/emoji/EmojiParser.java

@@ -84,6 +84,23 @@ public String transform(UnicodeCandidate unicodeCandidate) {
     return parseFromUnicode(input, emojiTransformer);
   }
 
+  /**
+   * Replace all emojis with character
+   *
+   * @param str the string to process
+   * @param replacementString replacement the string that will replace all the emojis
+   * @return the string with replaced character
+   */
+  public static String replaceAllEmojis(String str, final String replacementString) {
+    EmojiParser.EmojiTransformer emojiTransformer = new EmojiParser.EmojiTransformer() {
+      public String transform(EmojiParser.UnicodeCandidate unicodeCandidate) {
+        return replacementString;
+      }
+    };
+
+    return parseFromUnicode(str, emojiTransformer);
+  }
+
 
   /**
    * Replaces the emoji's aliases (between 2 ':') occurrences and the html

src/test/java/com/vdurmont/emoji/EmojiParserTest.java

@@ -29,6 +29,22 @@ public void parseToAliases_replaces_the_emojis_by_one_of_their_aliases() {
     );
   }
 
+  @Test
+  public void replaceAllEmojis_replace_the_emojis_by_string() throws Exception {
+    // GIVEN
+    String str = "An 😀awesome 😃string with a few 😉emojis!";
+
+    // WHEN
+    String result = EmojiParser.replaceAllEmojis(str, ":)");
+
+    // THEN
+    assertEquals(
+      "An :)awesome :)string with a few :)emojis!",
+      result
+    );
+  }
+
+
   @Test
   public void parseToAliases_REPLACE_with_a_fitzpatrick_modifier() {
     // GIVEN