upgrade safe-wipe and fix a few typos

[bmpitzen]

• after an update to safe-wipe to remove a dependency on Q, this bumps the version in sassdoc
• fixed a few typos in the Guidelines file

[bmpitzen]

@pascalduez I see you are also a maintainer here on sassdoc. Mind taking a look at this update too?

[pascalduez]

Hey @bmpitzen,

thanks for the PR, looks good to me.

Could you give us a bit more details about the issue you encounter with Q? You mentioned it's deprecated, but I'm afraid that might be true as well for most of dependencies here...
What makes me uncomfortable: we don't have a clear Node version support policy, we transpile with Babel for Node 4, but our old Travis config is set to test on Node 6, 8 and higher.
So theoretically that would be a breaking change as well, but I'm not keen on releasing a major version with only that change, given the poor maintenance state of the project, unfortunately.

First, I'll setup Github actions to be able to run the tests on PRs, that should give a tad more "confidence".