Decouple serverside-adapter from serverside

engineyard-serverside-adapter doesn't allow us to evolve serverside as fast as we could because both versions are coupled, when in reality the adapter never changes.

Changes:

1. Allow to specify the serverside version we want to be sticked to and only install this version if there is no a greater version.
2. Allow to use serverside versions greater than the want we specify.
3. Do not call a specific version of serverside, it calls the most recent version installed in the instance.

Benefits:

1. We can have faster serverside development cycles.
2. We can add serverside to the resin distribution package and we won't need to upgrade awsm nor cli anymore to bump a new version of serverside. Now that we have stacks it will allow us to get rid of ruby 1.8.6 faster, yay!!!!