move apps list into separate command
move dynos list into separate command
move releases list into separate command
breakout addons into separate command, remove ls
Split NewRequest() and DoReq() out of APIReq().

This will allow the caller to make changes to the API request (such as
adding headers where appropriate).
Use new v3 log-sessions API. Fixes #73.

Also remove Acceptor interface and url.Values option, they are no longer used.

Because of removed Acceptor interface, NewRequest no longer requires v.
Rename tail -p to -d to be consistent w/ 'dyno' noun