Addon(info) - wrap prop values in braces

[bmv437]

Issue:
Based on the code around braceWrap I believe the intention was to surround non-string prop values in curly braces. This would make it pretty easy to copy/paste react code from storybook into an app.

What I did

I surrounded non-string prop values in html encoded curly braces.

How to test

addon-info "Story Source" used to look like:

<Component prop=value />

now looks like

<Component prop={value} />

Is this testable with jest or storyshots?
Yes, with storyshots. I've updated them.

Does this need a new example in the kitchen sink apps?
No.

Does this need an update to the documentation?
No.

If your answer is yes to any of these, please make sure to include it in your PR.

[codecov]

Codecov Report

Merging #1915 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1915   +/-   ##
=======================================
  Coverage   21.29%   21.29%           
=======================================
  Files         261      261           
  Lines        5743     5743           
  Branches      694      684   -10     
=======================================
  Hits         1223     1223           
- Misses       3993     3997    +4     
+ Partials      527      523    -4

Impacted Files	Coverage Δ
addons/info/src/components/PropVal.js	41.41% <100%> (ø)	⬆️
app/vue/src/server/config/babel.js	0% <0%> (-100%)	⬇️
app/vue/src/server/babel_config.js	0% <0%> (-77.42%)	⬇️
lib/ui/src/modules/ui/configs/handle_keyevents.js	33.33% <0%> (ø)	⬆️
lib/ui/src/modules/api/configs/init_api.js	40.47% <0%> (ø)	⬆️
lib/ui/src/modules/ui/containers/layout.js	12.5% <0%> (ø)	⬆️
...res__/update-addon-info/update-addon-info.input.js	0% <0%> (ø)	⬆️
addons/knobs/src/KnobManager.js	32% <0%> (ø)	⬆️
addons/knobs/src/components/PropForm.js	8.51% <0%> (ø)	⬆️
... and 23 more

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[ndelangen]

It looks good to me, what do you think @usulpro @Hypnosphi ?

[Hypnosphi]

Excellent!

[Hypnosphi]

@ndelangen I think it's rather a bugfix then a feature

[ndelangen]

Welcome to the team @bmv437 !!