Add Support for addition Sentry Fields (Users, Request Data, Environment, Release)

[cycomachead]

Sorry this is one big PR. I've been meaning to try to upstream some changes for a while. If there's interest, consider this the start of a conversation — I can try to break this up as necessary.

Essentially, I've been using raven-lua pretty successfully in a Lapis (OpenResty) project. I've needed to extend this to support a few additional fields more common in traditional user-facing web apps.

• Adds environment as a static property to the event payload, passed in during initialization
• addsserver_name. Can be passed in or defined with get_server_name
• adds release. Same deal as above. :)
• Allows user and contexts tables to be passed to send_report
• Now includes a default version of get_request_data which was contributed to my fork by danifbento
• Also fixes a small typo. :)

[DDevine]

It isn't that big of a merge... And it looks good to me.

[nevmerzhitsky]

Why it wasn't merged, guys? :'(

[nevmerzhitsky]

@jdesgats consider merge of this, please

[amo13]

Please merge