updating contributors file
updating contributors file

giving credit where credit is due

Testing Done:
https://travis-ci.org/ebubae/intellij-pants-plugin/builds/141471940
See more extensive testing below:

```python
>>> if 'Ebube Chuba' in open('CONTRIBUTING.md').read():
...   print("All tests passed")
... else:
...   print("All tests failed, try again.")
...
All tests passed
```

Reviewed at https://rbcommons.com/s/twitter/r/4040/

wisechengyi/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,pantsbuild/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,wisechengyi/intellij-pants-plugin,pantsbuild/intellij-pants-plugin