Support packages that don't live at the root of a VCS checkout

[agroszer]

SVN 1.7 does not put a .svn folder all over the place, so if the checkout root is not the same as the package root (e.g. full repo checkout, packages in subfolders) it refuses to work.

[mgedmin]

This actually affects all version control systems, since check-manifest currently looks for .svn/.hg/.git/.bzr in the source tree root.

Shouldn't be too hard to modify get_vcs_files() to walk parent directories until it finds a VCS directory.

[mgedmin]

Actually, it may be a bit harder than that: I'll have to verify that the various VCS-specific command lines list files from that subdirectory only.

I don't expect this to be hard, but it may take some time.

[mgedmin]

This will be fixed in 0.14.