For both generator core and the plugins, log package and git information

Preview:

```
...
[init] Package generator-core v1.0.0
[init] Git branch dk/versions @ af6bf8be2999d8a80598da4a9b2d793e15aefea7
[init] Node.js version: {"http_parser":"1.0","node":"0.10.15","v8":"3.14.5.9","ares":"1.9.0-DEV","uv":"0.10.13","zlib":"1.2.3","modules":"11","openssl":"1.0.1e"}
[init] OS: Darwin 12.4.0 (x64), platform: darwin
...
[init] Generator started!
Loading plugins from /Users/dkehrig/Documents/Photoshop/Generator/plugins
Loading plugin "generator-assets" from directory "/Users/dkehrig/Documents/Photoshop/Generator/plugins/assets.generate"
[generator-assets] Package generator-assets v1.0.0
[generator-assets] Git branch master @ 6dd7a57562393a2b90d0b077e3df8fc2aba3fa26
initializing generator-assets plugin with config {}
...
```