Add hipchat_options for capistrano

If you send messages with API v2, you can configure it like below:

```
set :hipchat_options, {
  :api_verison => "v2"
}
```
Set default hipchat_color option to yellow

The `color` parameter is expected to be a String.
The yellow color is used as default in HipChat::Room#send.
Merge pull request #82 from a2ikm/capistrano_hipchat_options

Add hipchat_options for capistrano to select API version