Build & deployment improvements

Use the current deployment dir instead of creating a new one if
hot_deploy is enabled
Build & deployment improvements

Split activate into activate (self) and activate_many (others gears)

Fix scale up so hot_deploy marker is ignored and a full deploy is
performed
Update unit tests
Build & deployment improvements

Cleanup some TODOs

Reenable 'gear activate' to activate all gears

Don't stop the web proxy cart on rollback

Replace puts calls with buffer concatenation in cartridge_actions.rb