Add support for PUT requests

[fylie]

What does this PR do?

This PR adds support for the PUT HTTP request method.

Why is it important/What is the impact to the user?

Supporting PUT is important as some APIs (for example the Elasticsearch API) don't support POST/PUT interchangeably.

I noticed that there were multiple other PRs that attempted to add PUT functionality #32 and #28, but they haven't been merged due to reasons unrelated to this functionality.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Related issues

• added option 'ignorable_codes' to also return failed REST calls #32
• Add forms in body_format and PUT in VALID_VERBS #28

[cla-checker-service]

💚 CLA has been signed

[jsvd]

LGTM thanks for the contribution!

[jsvd]

Published as logstash-filter-http-1.1.0