Try to convert objects with numeric keys to lists

This is mostly intended to provide a way to specify lists
on the command line via Java properties, like -Dfoo.0 -Dfoo.1

Fixes #69
Convert numerically-indexed objects to arrays in concatenations
Discuss conversion of objects to arrays in the spec
Link to examples and overview from Config, ConfigFactory docs

Trying to help people find the big-picture points they need to see.
Mention the need to call resolve() in the Config docs
mention in Config.resolve docs that ConfigFactory methods may call it for you
Explain merging a bit better in withFallback docs
Fix javadoc warnings
v1.0.1
back to -SNAPSHOT and put 1.0.1 in the README