Remove third-party convenience dependencies from the repo

Instead, download them during "make deps" (unless already installed).
Use ocaml-base64 instead of old ocamlnet's base64 implementation
Fix deps build on osx
Bring NOTICE and copyright information up-to-date
Add a missing copyright header

Also, add comments clarifying use of camlidl.
Bump copyright year
Add missing copyright headers and license information
Enable Travis-CI build on osx