JSON API Rework
Note: This breaks json-level api compatibility and trace url bookmarks.

1) Support hex-based URLs like the previous zipkin-web:
https://github.com/twitter/zipkin/issues/211

2) Fix port numbers to be unsigned (no negative ports)

3) Change json hosts to be dotted-quad strings instead of network-order ints
Merge pull request #211 from twitter/hexurls

JSON API Rework
Note: This breaks json-level api compatibility and trace url bookmarks.

1) Support hex-based URLs like the previous zipkin-web:
https://github.com/twitter/zipkin/issues/211

2) Fix port numbers to be unsigned (no negative ports)

3) Change json hosts to be dotted-quad strings instead of network-order ints