Because we do NOT offer binaries for now, so before you install the gopm, you should have already installed Go Development Environment with version 1.1 and later.
The executable will be produced under `$GOPATH/bin` in your file system; for global use purpose, we recommand you to add this path into your `PATH` environment variable.
- No requirement for installing any version control system tool like `git`, `svn` or `hg` in order to download packages(although you have to install git for installing gopm though `go get` for now).
- Download, install or build your packages with specific revisions.
- When build program with `gopm build` or `gopm install`, everything just happen in its own GOPATH and do not bother anything you've done.