Refactor and fork vbucket

- Rewrite vbucket.c to be cleaner
- Add simple unit test
- Move header files into <libcouchbase/*>
- Mode source files into src/
- Add support for SSL ports (as of 3.0.0-367)

Change-Id: I277ef1e540556fd6c88fe00c09d1fc0709439f9b
Reviewed-on: http://review.couchbase.org/37337
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>