LFS support?

It looks like git-remote-dropbox doesn't support LFS. When I tried it I got the following message:

```
Remote "origin" does not support the Git LFS locking API. Consider disabling it with:
$ git config lfs.https://dropbox////[REPO_NAME].git/info/lfs.locksverify false
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
Uploading LFS objects: 0% (0/100), 0 B | 0 B/s, done.
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
...
```

Even after running that command I still get:

```
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
Uploading LFS objects: 0% (0/100), 0 B | 0 B/s, done.
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
batch request: ssh: Could not resolve hostname dropbox: nodename nor servname provided, or not known: exit status 255
...
```

Is this expected to work with LFS?

Start by reproducing the reported Git LFS failure with git-remote-dropbox and a repository containing LFS objects. The issue does not name files or describe the expected implementation, so first read the remote-helper entry point and confirm with maintainers whether the goal is LFS support or documenting that it is unsupported. Done means the project has an agreed behavior for Git LFS.

索引モデルが issue の本文から書いたものです。