Use Cosmiconfig

[shellscape]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

This PR introduces the use of cosmiconfig for finding and loading both webpack.config.js and provides support for an independent webpack-serve settings file, which will be merged with any serve settings in webpack.config.js.

This will provide the ability to set project-level defaults for webpack-serve, making use of multiple configs with the same serve settings easier to maintain. This will come in handy for addressing options like clipboard (introduced in #40), whereby a top-level .servcerc for instance, would allow for disabling the feature across the board.

Breaking Changes

None

Additional Info

[codecov]

Codecov Report

Merging #41 into master will increase coverage by 0.8%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master      #41     +/-   ##
=========================================
+ Coverage   91.05%   91.86%   +0.8%     
=========================================
  Files           7        7             
  Lines         257      258      +1     
=========================================
+ Hits          234      237      +3     
+ Misses         23       21      -2

Impacted Files	Coverage Δ
cli.js	96.77% <100%> (+6.45%)	⬆️
lib/options.js	87.34% <100%> (ø)	⬆️
index.js	95.74% <100%> (+0.09%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8d160d8...71cf270. Read the comment docs.