implement 'Timer Mode'

 * add shotgun at development environment
 * implement Rubyistimer mode
  * use same template and script each tokei and timer
  * partialize differences between tokei and timer
 * usage
  /timer[?limit=TIME_LIMIT]
  * TIME_LIMIT = unit: minutes, default: 5, allowed: 1 .. 99
Merge pull request #150 from kwappa/timer-mode

implement 'Timer Mode'