increase cache size & dont cache full size media (#710)

app/src/main/java/com/keylesspalace/tusky/fragment/ViewMediaFragment.java

@@ -209,6 +209,7 @@ public final class ViewMediaFragment extends BaseFragment {
         Picasso.with(getContext())
                 .load(url)
                 .noPlaceholder()
+                .networkPolicy(NetworkPolicy.NO_STORE)
                 .into(photoView, new Callback() {
                     @Override
                     public void onSuccess() {

app/src/main/java/com/keylesspalace/tusky/util/OkHttpUtils.java

@@ -92,7 +92,7 @@ public class OkHttpUtils {
         specList.add(fallback);
         specList.add(ConnectionSpec.CLEARTEXT);
 
-        int cacheSize = 10*1024*1024; // 10 MiB
+        int cacheSize = 25*1024*1024; // 25 MiB
 
         OkHttpClient.Builder builder = new OkHttpClient.Builder()
                 .addInterceptor(getUserAgentInterceptor())