Improve license compliance

The code is now in compliance with the Apache Software License 2.0. `LICENSE` and `NOTICE` files have been added, headers added to files that were missing them, and the text of the license has been placed in the `README.md` file.
Merge branch 'license'
Upgrade to Jackson 2

Previously this code worked against the Jackson 1.x line.  Now that
the Jackson 2 line has stabilized the code has been updated to use it
instead.  This involved changing the dependencies as well as updates
to the code for import and API changes.

This change partially addresses #2.
Merge branch 'jackson-2'