Disable image keyboards for SDK < 5.0

Fixes #6045
// FREEBIE

src/org/thoughtcrime/securesms/components/ComposeText.java

@@ -131,7 +131,7 @@ public class ComposeText extends EmojiEditText {
       editorInfo.imeOptions &= ~EditorInfo.IME_FLAG_NO_ENTER_ACTION;
     }
 
-    if (Build.VERSION.SDK_INT <= 13) return inputConnection;
+    if (Build.VERSION.SDK_INT < 21) return inputConnection;
     if (mediaListener == null)      return inputConnection;
     if (inputConnection == null)    return null;