Added import/export to the demo app

- discovered private key length was wrong - fixed
- as things are broken anyway, refactored flyway migrations - you'll need to delete ~/jabit.*.db

wif/src/test/java/ch/dissem/bitmessage/wif/WifImporterTest.java

@@ -64,6 +64,8 @@ public class WifImporterTest {
         assertEquals(320, identity.getPubkey().getNonceTrialsPerByte());
         assertEquals(14000, identity.getPubkey().getExtraBytes());
         assertNotNull("Private key", identity.getPrivateKey());
+        assertEquals(32, identity.getPrivateKey().getPrivateEncryptionKey().length);
+        assertEquals(32, identity.getPrivateKey().getPrivateSigningKey().length);
     }
 
     @Test