Git LFS support

[fabian-z]

PR as requested by @lunny, merge conflicts originate from gitea commits. I'm using Gogs as upstream so I can't promise to correct those. Original PR: gogs/gogs#3868

Feature requested in gogs/gogs#1322

This PR implements Git LFS support for Gogs, supporting the legacy v1 API as well as the current batch v1 API.

Originally imported LFS server code base from https://github.com/git-lfs/lfs-test-server.

Features:

• Uses recommended paths with HTTP and SSH remotes, no custom user settings necessary
• Supports basic authentication with user credentials
• Supports authentication with SSH (passing JWT under the hood)
• Supports no authentication when pulling public repositories (however git-lfs still asks for credentials, where the prompt can be skipped - likely a bug in git-lfs)
• Settings transparently integrated into installation process
• Removes LFS objects when repositories are deleted. Works with forks (e.g. when parent repository is deleted)

Notes:

• https://github.com/fabian-z/gogs/commit/58375e6b8648527597339b4b4b042fa71cf41b76 was necessary to import github.com/dgrijalva/jwt-go, as well as fix Build error with 0.9.99.0915 gogs/gogs#3732
• Does not yet delete LFS objects when repository is removed
• https://github.com/fabian-z/gogs/commit/0344f98166058a0e58d425fc5d25967c6f5901cc regenerates bindata in order to apply locale additions from https://github.com/fabian-z/gogs/commit/c166480ab0b5118ed9b7fbecb257406fdfab2daf

Looking forward to your review!

[lunny]

This will resolved #80

[strk]

Can you please rebase and avoid generating bindata.go in the PR ?
Also don't bother touching glide, we use govendor here

[fabian-z]

@strk

Please read the note in my PR. I sent this PR to gogits/gogs and only copied it here on request by @lunny. As my time is limited and my upstream is Gogs, I currently won't be able to rebase / fix issues for gitea. Thanks for your understanding.

[bkcsoft]

Why not use LFSAuthenticateVerb here?

[strk]

On Tue, Nov 08, 2016 at 07:28:27AM -0800, bkcsoft wrote:

• "git-upload-pack":    models.ACCESS_MODE_READ,
  

• "git-upload-archive": models.ACCESS_MODE_READ,
  

• "git-receive-pack":   models.ACCESS_MODE_WRITE,
  

• "git-upload-pack":      models.ACCESS_MODE_READ,
  

• "git-upload-archive":   models.ACCESS_MODE_READ,
  

• "git-receive-pack":     models.ACCESS_MODE_WRITE,
  

• "git-lfs-authenticate": models.ACCESS_MODE_NONE,
  

And I think those constants are named AccessModeNone etc. now.
(but I understand the author is not interested in porting this to
Gitea)

[fabian-z]

Let me clarify on my statement.
Please correct me if I'm wrong or I misunderstood the situation, but Gitea seems to be maintained as a constantly rebased fork of Gogs (like a changeset maintained by downstream distributions). Therefore, my priority would be to get this reviewed and merged upstream with Gogs. If this is possible, a rebase would bring the feature to Gitea and the changeset which needs to be maintained can remain as small as possible.
However, my main interest is to bring this feature into active usage and to have continued development together with other contributors.
If my PR is not reviewed or merged into Gogs master in a reasonable amount of time, I'd be glad to work with you to port my changes to Gitea.

[strk]

@fabian-z you misunderstood: Gitea will never be rebased against Gogs, but rather continue on its own.
The fork was driven by the willingness to have a more open development method, so you're welcome to join the effort. You can compare Gogs and Gitea activity via the Pulse screen:

https://github.com/go-gitea/gitea/pulse
https://github.com/gogits/gogs/pulse

[fabian-z]

@strk
Thank you for elaborating on the project status. Indeed I must have misjudged on first glance - thanks again for pointing me to the Pulse graphs.
I definitely prefer an open, collaborative development, too.
I will try to rebase this on Gitea master and provide a new PR incorporating your reviews.