Release wGulp 0.6.1

PRs contained in this release:

https://github.com/Workiva/wGulp/pull/58
https://github.com/Workiva/wGulp/pull/60
https://github.com/Workiva/wGulp/pull/61

Diff Between Last Tag and Proposed Release: https://github.com/Workiva/wGulp/compare/0.6.0...Release_0.6.1

How To +10/QA
-------------

```bash
# skip the following steps if you've already initialized the project
git clone git@github.com:Workiva/wGulp.git
cd wGulp

# do not skip these!
git fetch && git checkout Release_0.6.1
Run unit tests
```