Support for GitLab artifacts

Part of gitlab-org/gitlab-ce!1584

TODO:

• Add artifacts directory configuration.
• Update nginx configuration for Gitlab to open up artifacts endpoint
• Compile NGINX with uploads module

cc @jacobvosmaer @ayufan

License of nginx-upload-module looks ok.

Compile error with uploads module:

Error:

    /var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c: In function 'ngx_http_upload_merge_ranges':
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c:1681:18: error: variable 'result' set but not used [-Werror=unused-but-set-variable]
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c: In function 'ngx_http_read_upload_client_request_body':
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c:2628:15: error: 'ngx_http_request_body_t' has no member named 'to_write'
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c:2687:7: error: 'ngx_http_request_body_t' has no member named 'to_write'
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c: In function 'ngx_http_do_read_upload_client_request_body':
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c:2769:57: error: 'ngx_http_request_body_t' has no member named 'to_write'
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c:2785:19: error: 'ngx_http_request_body_t' has no member named 'to_write'
/var/cache/omnibus/src/nginx-upload-module/ngx_http_upload_module.c:2877:45: error: 'ngx_http_request_body_t' has no member named 'to_write'
cc1: all warnings being treated as errors
make[1]: *** [objs/addon/nginx-upload-module/ngx_http_upload_module.o] Error 1
make[1]: *** Waiting for unfinished jobs....
make: *** [build] Error 2

Known issue apparently looking at the issues. One of the recommendations is to use a different branch.

mentioned in merge request !513 (closed)

This was postponed to 8.2.

Milestone changed to 8.2

In !535 (merged)

Status changed to closed