introduce HTTParty-configuration, fix #61

[barraq]

This commit introduces a new option attribute, namely httparty, that allows passing configuration down to HTTParty.
For instance to disable verification of self-signed certificates you can now do as follow:

client1 = Gitlab.client(endpoint: 'https://api1.example.com', private_token: 'user-001', httparty: {verify: false})

The list of HTTParty configuration attributes can be found at https://github.com/jnunemaker/httparty

[barraq]

@jvanbaarsen @NARKOZ ?

[jvanbaarsen]

@barraq Thanks!

[dblessing]

I think this is unnecessary. You can already pass any httparty config down via options hash. So, you would say 'options[:verify] = false' right?

The piece that allows setting a default set of options would be nice, but that portion of this pull is incomplete.

[jvanbaarsen]

@dblessing Ok, what do you suggest? Complete this PR, or revert the PR?

[barraq]

@dblessing are you sure about that? I first tried as you suggested but it appeared that options were not passed along to httparty or that they were ignored...

[dblessing]

Let me test and see.

[dblessing]

Oh, I see the issue. The options hash is not consistently implemented in this library. If it was passed directly, and not reassigned, it would work as expected :)

In some places the options hash is assigned to :query like this:
https://github.com/NARKOZ/gitlab/blob/master/lib/gitlab/client/users.rb#L14

Given this, I think we have to keep this change. We could make things consistent but that would undoubtedly break what people are already using.

@barraq Even with the changes you made, I would caution you that not all methods even bother to accept options. -- But I guess that's where the default options come in.