Add deployment key to .gitignore
Get revision when commit id is specific
new func ssh, check_ssh and use it with identity
Automate deployment with travis-ci

This commit should automatically deploy to servers when:

 - The repo slug is clicheio/cliche
 - The branch is master
 - The build is not a pull request
 - The job is the first one of the build

This commit has undergone tests in circumstances:

should pass on:
 - normal circumstance

should fail on:
 - when the slug is different
 - when the branch is different
 - when the build is a pull request and branch is master
 - when the build is a pull request and branch is not master
 - when the job is not the first one of the build