added thumbsup and thumsdown emoji voting with rspec tests

for Feature Request:
http://feedback.gitlab.com/forums/176466-general/suggestions/5063152-thumbsup-and-thumbsdown-emoji-should-be-counted-wh

**Thumbsup and thumbsdown emoji should be counted when voting**

Right now +1, -1, : +1 : and : -1 : are counted as votes in issues and merge requests, also include : thumbsup : and : thumbsdown : emoji

I have added tests for this voting and added voting with the thumbs emojis : thumbsup : and : thumbsdown :.