WIP on replacing Jackson with GSON

The motivator is that the Python clients are fussy about empty vs null.
Merge branch 'master' into gson_all_the_way
More WIP on gson
Merge branch 'master' into gson_all_the_way

Conflicts:
	fathomcloud-identity/src/main/java/io/fathom/cloud/identity/IdentityExtension.java
Force Sun provider for resumable MD5

We rely on the internal implementation!
Use lookupFile when resolving path for hostkey

Otherwise we don't get config-file relative path
Log if we can't deserialize a date in DateTypeAdapter
Make sure our new ReflectiveTypeAdapterFactory doesn't override the base factories
Remove references to jackson
Add XmlElement / XmlAttribute where the JSON rules don't match
Use DateTypeAdapter with GsonMessageBodyReaderWriter
Merge branch 'gson_all_the_way'