Implemented 'Extras' to 'User'

[wuh95]

#31

[bruno-garcia]

@wuh95 could you please rebase with master to fix the appveyor build?

[bruno-garcia]

@wuh95 Thanks a lot for helping!
I just left a couple comments to align with other SDKs, etc.

[codecov-io]

Codecov Report

Merging #32 into master will increase coverage by 0.06%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #32      +/-   ##
==========================================
+ Coverage   94.54%   94.61%   +0.06%     
==========================================
  Files          26       26              
  Lines         623      631       +8     
==========================================
+ Hits          589      597       +8     
  Misses         34       34

Impacted Files	Coverage Δ
src/Sentry.Protocol/User.cs	100% <100%> (ø)	⬆️

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[wuh95]

It seems like there is another error in the appveyor build now

[bruno-garcia]

@wuh95 right! It's fine this build will break when trying to upload artifacts to zeus.ci but the built itself is OK so I can merge it.

[wuh95]

@bruno-garcia When should I expect the merge? Because I want to use this change right away in my project :)

[bruno-garcia]

@wuh95 I can merge it today but there's only small point above to change. Could you please fiz that last one?
I'll publish a new version today.

[wuh95]

@bruno-garcia I overlooked that one, sorry. Everything should be right now :)

[bruno-garcia]

@wuh95 great! Thanks.
I'll publish a new version but I won't release Sentry yet so please make a direct reference to Sentry.Protocol using the new version.

[wuh95]

Ok, thank you!