I setup a test environment and re-produced the error:
$ cap install
(Backtrace restricted to imported tasks)
cap aborted!
No Rakefile found (looking for: capfile, Capfile, capfile.rb, Capfile.rb, /usr/lib/ruby/vendor_ruby/Capfile)
/usr/bin/cap:3:in `<main>'
(See full trace by running task with --trace)
$ cap --trace install
cap aborted!
No Rakefile found (looking for: capfile, Capfile, capfile.rb, Capfile.rb, /usr/lib/ruby/vendor_ruby/Capfile)
/usr/lib/ruby/vendor_ruby/rake/application.rb:684:in `raw_load_rakefile'
/usr/lib/ruby/vendor_ruby/rake/application.rb:94:in `block in load_rakefile'
/usr/lib/ruby/vendor_ruby/rake/application.rb:176:in `standard_exception_handling'
/usr/lib/ruby/vendor_ruby/rake/application.rb:93:in `load_rakefile'
/usr/lib/ruby/vendor_ruby/rake/application.rb:77:in `block in run'
/usr/lib/ruby/vendor_ruby/rake/application.rb:176:in `standard_exception_handling'
/usr/lib/ruby/vendor_ruby/rake/application.rb:75:in `run'
/usr/lib/ruby/vendor_ruby/capistrano/application.rb:15:in `run'
/usr/bin/cap:3:in `<main>'
Located Capfile
and ran the command
$ cap --rakefile /usr/lib/ruby/vendor_ruby/capistrano/templates/Capfile install
mkdir -p config/deploy
create config/deploy.rb
create config/deploy/staging.rb
create config/deploy/production.rb
mkdir -p lib/capistrano/tasks
create Capfile
Capified
It works.