Merge pull request #3 from Caleydo/add-issue-template

This repo has travis turned on, but no configuration was provided.
```
Could not find .travis.yml, using standard configuration.
...
$ rake
rake aborted!
No Rakefile found (looking for: rakefile, Rakefile, rakefile.rb, Rakefile.rb)
```

No connection to my commit, so going ahead and merging.