Added flag to disable output. Support forms.

[senglin]

While using the library, I found that the I needed the following capabilities which were not supported:

1. Generate curl requests using form options. (This current throws a String error)
2. Ability to turn off outputs from http-to-curl.
3. Bug: Specify url in the Options object is not supported. (This currently logs a curl request of http://localhost/)

Changes:

1. Added test for new scenario
2. Convert string to buffer before concatenating the chunks in the body
3. Added new parameter to turn off console log.
4. Tidy up some statement. Added comments.

[drgx]

Sorry for the slow responses, Thanks For your contribution.
Why this library need dockerfile?
Can you please remove the docker file and ignore, then I will merge this PR 🙇

Soon I will help to re-release this patch. Thanks for your contribution.