Add git status infos for 'meteor --version' when running meteor from checkout

The changes will show additional information extracted from ```git status``` when calling ```meteor --version``` from git checkout.

Old output:
```
Unreleased (running from a checkout)
```

New output:
```
Unreleased (running from a checkout) [BRANCH release-1.0-universal...origin/release-1.0-universal]
```
```
Unreleased (running from a checkout) [HEAD detached at release/METEOR@0.9.1]
```