Fix a crash caused by a null FingerprintManager

app/src/main/java/me/impy/aegis/ui/SlotManagerActivity.java

@@ -72,11 +72,11 @@ public class SlotManagerActivity extends AegisActivity implements SlotAdapter.Li
         // only show the fingerprint option if we can get an instance of the fingerprint manager
         // and if none of the slots in the collection has a matching alias in the keystore
         int visibility = View.VISIBLE;
-        if (FingerprintHelper.isSupported()) {
+        if (FingerprintHelper.getManager(this) != null) {
             try {
                 KeyStoreHandle keyStore = new KeyStoreHandle();
                 for (FingerprintSlot slot : _slots.findAll(FingerprintSlot.class)) {
-                    if (keyStore.containsKey(slot.getUUID().toString()) && FingerprintHelper.getManager(this) != null) {
+                    if (keyStore.containsKey(slot.getUUID().toString())) {
                         visibility = View.GONE;
                         break;
                     }

app/src/main/res/layout/fragment_authentication_slide.xml

@@ -25,7 +25,6 @@
         android:layout_marginTop="12dp"
         android:orientation="horizontal">
 
-
         <RadioGroup
             android:id="@+id/rg_authenticationMethod"
             android:layout_width="match_parent"