Release wGulp 0.7.0

PRs contained in this release:

https://github.com/Workiva/wGulp/pull/65
https://github.com/Workiva/wGulp/pull/64
https://github.com/Workiva/wGulp/pull/66
https://github.com/Workiva/wGulp/pull/67
https://github.com/Workiva/wGulp/pull/71
https://github.com/Workiva/wGulp/pull/69
https://github.com/Workiva/wGulp/pull/63
https://github.com/Workiva/wGulp/pull/73
https://github.com/Workiva/wGulp/pull/77

Diff Between Last Tag and Proposed Release: https://github.com/Workiva/wGulp/compare/0.6.1...Release_0.7.0

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_0.7.0
Run unit tests
```