Override hashCode when equals overridden

Java 8 added a warning for this:

https://bugs.openjdk.java.net/browse/JDK-6563143
Add missing @Override annotations
JCLOUDS-573: Make sure to destroy all nodes created in the tests
Prefer ByteStreams over ByteArrayOutputStream
Prefer Guava Hashing over MessageDigest
Use ByteSource methods to create test input

Also avoids excessive system calls due to unbuffered writes.  Finally
migrate repeatingArrayByteSource to ByteSources.
Prefer File.delete over File.deleteOnExit

The former has deterministic behavior and avoids resource leaks.
[JCLOUDS-392] Remove dependency from Maps2. Make jclouds-core packages optionally imported from jclouds-scriptbuilder.
JCLOUDS-471: Adds pool field to FloatingIP and updated related tests.