Adds a Clippy meme to the meme generator, which
listens for "it looks like you('re) <text>"

```
Hubot> hubot it looks like you're trying to use Hubot
Hubot> http://images.memegenerator.net/instances/33587375.jpg 
```

(Thanks to @jasonkarns for the suggestion)
Merge pull request #716 from searls/master

Add a Clippy meme to the meme_generator script.