Restrict availability zone, e.g.: -s availability_zone=us-east-1a
Document branch and availability zone switches
Bump version to 3.0.2
Whitespace
Change option from availability_zone to az

Easier to type :)
AZ/server information referenced by new key (instances, not servers)

This is for backwards compatibility - the hq server needs to keep serving
up the old response format for old capistrano-hivequeen libraries.
Merge pull request #3 from kickstarter/cap_availability_zones

Option to run commands on availability zones