Add initial set of contribution guidelines

[paultcochrane]

This change documents some of the steps required in order to contribute
to Net::HTTP in the hope that it helps newcomers to the project create
their first submission(s) and is submitted in response to a discussion
in #76. It includes a quick start guide for setting up a perlbrew
environment as well as how to install Dist::Zilla and how to use it to
install upstream dependencies. The document also describes the steps
necessary to create a pull request from a feature branch in a user's
forked repository.

The contribution documentation submitted here is a proposal: if anything here doesn't meet any implicit contribution guidelines you have, please let me know and I'm more than happy to update the patch and resubmit it. Also, if I've missed anything you would like to see in the contribution documentation, please just let me know and I'll add it to this pull request.

[karenetheridge]

I don't think we should be pushing contributors into using Dist::Zilla in any way in order to simply send a patch (and I say this as a very heavy dzil user, and author of dozens of plugins). It's available as an option, but to imply that it's required creates a high barrier that is too much for many to reach, and it's unnecessary.

The template file I use for my distributions is here, offering a much simpler path to running tests for the purposes of sending a patch: https://github.com/karenetheridge/Dist-Zilla-PluginBundle-Author-ETHER/blob/master/share/CONTRIBUTING

[paultcochrane]

Thanks for reviewing the patch so quickly! :-)

I don't think we should be pushing contributors into using Dist::Zilla in any way in order to simply send a patch (and I say this as a very heavy dzil user, and author of dozens of plugins). It's available as an option, but to imply that it's required creates a high barrier that is too much for many to reach, and it's unnecessary.

My apologies for implying that Dist::Zilla is required in order to create and send patches, that wasn't my intent. I'd assumed that Dist::Zilla was the recommended way to install dependencies and run the tests from @oalders's comment in #76 that he usually uses dzil. Looking again at his comment just now, I should have just documented using the cpanfile and prove as he mentioned. My bad: sorry :-/

I wasn't aware of your CONTRIBUTING file; would it be best to simply replace my patch with your CONTRIBUTING file? Or should I extend the patch I wrote to recommend (say) cpanminus with prove in addition to the use of Dist::Zilla? Or should the use of Dist::Zilla be avoided in the contributing docs? My apologies for the many questions; I'd like to submit something that you can use as-is rather than having to make major changes to it after submission.

[oalders]

@paultcochrane I think @karenetheridge's CONTRIBUTING.md is a good starting point, but we'd likely need to amend it a bit for our purposes. It would be good if we could have a CONTRIBUTING.md which could be added to most (or all) of the other libwww-perl distributions. So, as long as we have something fairly generic that doesn't push anyone towards Dist::Zilla that would already be a huge improvement.