create a symlink for the repo itself during save

This change is to create a symlink to the top of the repo at the proper location within `Godeps/_workspace/src`.
This is so that you can build a go project without it being in a proper `GOPATH` location.

Lets say you have a project `github.com/acmeco/rocket`, which has go files with `import`s such as `github.com/acmeco/rocket/engine`. When `go build` tries to build them, it's going to look for `rocket/engine` in the `GOPATH` locations. If the repo is not in such a location, it will fail.

This has several potential uses. The 2 reasons we need this change are:
1. When using jenkins to build from a repo, jenkins checks the source out to predefined location which cannot be controlled.
2. When building a repo within a docker container, it alleviates the need for having to figure out the path structure of where the repo should be placed within the container.

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So with this change, you would have a symlink at `Godeps/_workspace/src/github.com/acmeco/rocket` which points to `../../../../../` (the top of the repo).