Joda-time as required dependency for REST API implementations with AWS Lambda

Tried excluding Joda-time from a function's implementation for AWS Lambda and got next error:
```
java.lang.ClassNotFoundException: org.joda.time.DateTime: lambdainternal.util.ReflectUtil$ReflectException
lambdainternal.util.ReflectUtil$ReflectException: java.lang.ClassNotFoundException: org.joda.time.DateTime
Caused by: java.lang.ClassNotFoundException: org.joda.time.DateTime
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
```
This required dependency adds extra 0.5 megabytes to the resulting "fat jar". Extra jar size requires reserving more memory for the function to prevent Metaspace issues. But Joda-time itself is not of much use while using Java 8 (and earlier Java versions are not supported in AWS Lambda anyway), so this limitation is unnecessary.

Maybe it's time to get rid of Joda-time? At least in some "next gen" version, for example?

P.S.: Maybe it's a duplicate of #35 , but I just wanted to bring extra reasons to your attention.