Add support for outlined buttons

[patrick91]

No description provided.

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[patrick91]

I signed it!

[googlebot]

CLAs look good, thanks!

[kfranqueiro]

Thanks for the PR. Outlined buttons were actually renamed from stroked, so this PR should replace any instances of stroked with outlined. Currently both exist in this PR.

See #57.

cc @moog16 since he entered all of the tasks necessary for upgrading to MDC Web 0.35.

[patrick91]

@kfranqueiro I didn't notice! Thanks, I've updated :)

[codecov-io]

Codecov Report

Merging #74 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #74   +/-   ##
=======================================
  Coverage   98.86%   98.86%           
=======================================
  Files          18       18           
  Lines         617      617           
  Branches       49       49           
=======================================
  Hits          610      610           
  Misses          7        7

Impacted Files	Coverage Δ
packages/button/index.js	92.85% <ø> (ø)	⬆️

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[moog16]

Changes look good to me. I'm going to run it on my side and get the screenshot tests working since #71 is still an issue.

Because of #71 you cannot run the tests against TravisCI. So what I'll do is:

1. fork your branch
2. create a PR
3. Link this PR and the new PR together
4. Once tests pass I will close the new PR and merge this one (to give you the credit you deserve).

[moog16]

Related screenshot tests PR: #78.

@patrick91 could you please sign it?

[moog16]

@patrick91 #78 tests are passing! Will merge :)

[moog16]

Looks good per #78