set utf-8

Add utf-9 encoding code for using custom status symbol


## Example

```
# status indicators
STAGED = os.environ.get('VCPROMPT_STAGED', '⚙')
MODIFIED = os.environ.get('VCPROMPT_MODIFIED', '±')
UNTRACKED = os.environ.get('VCPROMPT_UNTRACKED', '✘')
```