why --bucket option is not available on latest master build?

Hi,
it's strange the -b bucket in README seemingly disappears?
```
$./bolter 
NAME:
  bolter - view boltdb file interactively in your terminal

VERSION:
  2.0.1

USAGE:
  bolter [global options]

GLOBAL OPTIONS:
  --file FILE, -f FILE  boltdb FILE to view
  --help, -h            show help
  --version, -v         print the version
  ```
