Schema Discovery

The purpose of this PR is to rework the schema discovery process, so that:

1. schema names are more predictable, especially when "$ref" entries are present in the schemas.  #164
2. nested schemas can be inner classes or use the current naming structure. #125
3. the POJO generation process can be configured in a way native to the tool being used.

This PR is a work in progress.  Currently, the following changes are included:

1. Some m2e lifecycle mappings have been added, to clean up eclipse warnings.  This could be moved into another PR or removed.
2. The current schema discovery code has been moved from the CLI module to PojoGenerator in the core module.  This is a verbatim move at this point.
3. The Maven, Ant, and Gradle modules have been updated to depend on the core module.

Planned next steps:

1. Convert PojoGenerator into an instance based class with fluid api.
2. Allow clients of the generator to specify the schema discovery process.
3. Update the rules, so that generation can happen in 2 phases.