Adds challenge rating to monster cards.

Android/app/src/main/java/com/majinnaibu/monstercards/ui/monster/MonsterFragment.java

@@ -301,6 +301,14 @@ public class MonsterFragment extends Fragment {
             }
         });
 
+        final TextView monsterChallenge = root.findViewById(R.id.challenge);
+        monsterViewModel.getChallenge().observe(getViewLifecycleOwner(), new Observer<String>() {
+            @Override
+            public void onChanged(String challengeRating) {
+                monsterChallenge.setText(Html.fromHtml("<b>Challenge</b> " + challengeRating));
+            }
+        });
+
         return root;
     }
 }

Android/app/src/main/java/com/majinnaibu/monstercards/ui/monster/MonsterViewModel.java

@@ -48,6 +48,8 @@ public class MonsterViewModel extends ViewModel {
         mSenses.setValue("");
         mLanguages = new MutableLiveData<>();
         mLanguages.setValue("");
+        mChallenge = new MutableLiveData<>();
+        mChallenge.setValue("");
     }
 
     private MutableLiveData<String> mName;
@@ -126,6 +128,10 @@ public class MonsterViewModel extends ViewModel {
     public LiveData<String> getLanguages() {
         return mLanguages;
     }
+    private MutableLiveData<String> mChallenge;
+    public LiveData<String> getChallenge() {
+        return mChallenge;
+    }
 
     private Monster mMonster;
     public void setMonster(Monster monster) {
@@ -149,5 +155,6 @@ public class MonsterViewModel extends ViewModel {
         mConditionImmunities.setValue(mMonster.getConditionImmunitiesDescription());
         mSenses.setValue(monster.getSensesDescription());
         mLanguages.setValue(mMonster.getLanguagesDescription());
+        mChallenge.setValue(mMonster.getChallengeRatingDescription());
     }
 }