Swagger-bundler

- postscript_hook

- prefixing targets responses,definisions -> responses,definisions,parameters

- fix case: ctx.data has 'responses' data (but value is None)
- fix watching generated file

- watch option is supported

- gentle warning message on FileNotFoundError
- bundle command with `--namespace` option
- qualified import (e.g. x-bundler-compose with 'foo.yaml as F')

- adding readme and examples
- support json format(input/output)