Initial commit.  Implements universal intermediary data representation,
with import and export to and from JSON, as well as reader and writer
implementations for the Legacy SQLite database.
Create README.md
Adds support for H2, and migrating to and from H2 and Legacy SQLite.  Refactors the intermediate model classes (i.e. removes default constructors, moves table field name constants to base class to reduce redundancy).
Refactors table field name constants to reflect the non-legacy names being the defaults.
Moves into test-scope those classes tied to vendor-specific dependencies (i.e. SQLite and H2 JDBC drivers), so this project can be more cleanly packaged as an artifact for use in different FitnessJiffy versions.
Renames project from "fitnessjiffy-data" to "fitnessjiffy-etl".
Refactors main package name from "data" to "etl", adds empty constructors to model objects to avoid JSON marshalling/unmarshalling problems, removes dependency on Guava library.
Removes unnecessary custom Set and Map types.
Merge branch 'master' of https://github.com/steve-perkins/fitnessjiffy-etl