WIP: Changing  import paths for moving the repo and some fixes related to tests

1. Names, paths, and import paths are changed from `racker/go-agent-endpoint` to `virgo-agent-toolkit/go-agnet-endpoint`. Nothing special here.

2. While working on 1, I encountered a bug, or an improperly designed feature related to git (<= 1.7.9). Before 1.7.10, when doing `git submodule update --init --recursive`, `.git/modules/<path>/config` has an absolute path assigned for `[core]`, `worktree`. Since `precise64` (the one used for Vagrant right now) has git-1.7.9, it suffers from this. If `git submodule update --init --recursive` runs within Vagrant VM, the `config` file would have an absolute path that corresponds to FS within VM (`/data/gopath/src/github.com/virgo-agent-toolkit/<blah blah>` in this case) and that breaks the git repository on host OS. Even `git status` wouldn't work on host OS, complaining `fatal: not a git repository`. This PR removes submodules initialization from puppet, which means the responsibility of cloning/init submodules is transferred from VM to host, i.e. user needs to `git clone --recursive` or initialize submodules manually.