Started adding code

- Added eclipse project files for easy importing.
- Added build file for use without eclipse.
- Added third-party libraries (junit, hamcrest).
- Added Interval class and tests.

The user is expected to resolve the dependencies on InPUT4j
for now. Once an "official" v0.5 release of InPUT4j is avilable,
the libraries will be updated to make the repository
self-contained.