Read application.rb as UTF-8 (Invalid byte sequence error)

`zeus start` threw me the following error:

```
/Users/mikko/.rvm/gems/ruby-1.9.3-p448/gems/zeus-0.13.3/lib/zeus/rails.rb:85:in `scan': invalid byte sequence in US-ASCII (ArgumentError)
	from /Users/mikko/.rvm/gems/ruby-1.9.3-p448/gems/zeus-0.13.3/lib/zeus/rails.rb:85:in `boot'
	from /Users/mikko/.rvm/gems/ruby-1.9.3-p448/gems/zeus-0.13.3/lib/zeus.rb:166:in `run_action'
	from /Users/mikko/.rvm/gems/ruby-1.9.3-p448/gems/zeus-0.13.3/lib/zeus.rb:54:in `block in go'
	from /Users/mikko/.rvm/gems/ruby-1.9.3-p448/gems/zeus-0.13.3/lib/zeus/load_tracking.rb:7:in `features_loaded_by'
	from /Users/mikko/.rvm/gems/ruby-1.9.3-p448/gems/zeus-0.13.3/lib/zeus.rb:53:in `go'
```

Apparently the error was due to the fact that my [application.rb](https://github.com/sharetribe/sharetribe/blob/master/config/application.rb) file is UTF-8 and it contains some localization configs including Chinese, Russian, etc. characters.

Adding `:encofing => 'utf-8' solved the issue.