update for capistrano 3.x

Here are the main notes:
- making use of Cap 3.x set/fetch changes
- updated hook dependencies
- making use of Cap 3.x ask method along with passing procs to set_default for evaluation at fetch time
- bumped up version to 0.1.0

2 things that need to be resolved:
- ask via proc is working for things like :nginx_server_name which are fetched in tasks.rb, but :unicorn_workers which is fetched in erb template is not getting to the console
- something during unicorn tasks is leaving behind /tmp/[app name]/ as a dir which will cause nginx tasks to blow up when trying "mv" commands

I'll leave it to you whether you want to merge to master, a new branch, or at all even.

thanks!