Default constructor workaround for Android 4.2+

The existing default constructor workarounds at SerializerPojo fails since Android 4.2, making a no-arg constructor required for serialized classes.

Solves this: #295 

This overcomes the changes in android introruced in [this commit](https://android.googlesource.com/platform/libcore/+/a40dc9f768eb02dcfd7b1a659333757b148f7bec%5E!/luni/src/main/java/java/io/ObjectStreamClass.java) - the constructor ID is now a `long`.