Fix name typo uidfile SSHFS Params List

[tjlauer]

Fix param name typo in SSHFS Params List.

• oidfile => uidfile

When using parameter idmap=file SSHFS expects a file path for uidfile and/or gidfile.
Setting the option oidfile does not satisfy either options.

I believe this could partially resolve #209 as far as user mapping is the only cause.
Using private key files for auth and/or domain users could be another source for the issue, but that's unrelated to this PR.

[evsar3]

Thanks for contribution @tjlauer, but I don't think I'm going to release new versions of v1.x, but I will take your fix into the v2 which is in currently in development.