ACardEmulator: Added F-Droid build flavor with FOSS only

- avoid precompiled JARs for JCardSim
- use gradle's shadow plugin to relocate JCardSim's use of Bouncycastle
- removes JCardSim's Hello world applet
- use vJCRE to avoid importing Oracle's api_classic.jar

(We may use vJCRE as full replacement for JCardSim in the future, but
JCardSim is currently the choice with more features and support)

ACardEmulator/ACardEmulator.iml

@@ -13,7 +13,7 @@
     <content url="file://$MODULE_DIR$">
       <excludeFolder url="file://$MODULE_DIR$/.gradle" />
     </content>
-    <orderEntry type="jdk" jdkName="1.8" jdkType="JavaSDK" />
+    <orderEntry type="inheritedJdk" />
     <orderEntry type="sourceFolder" forTests="false" />
   </component>
 </module>