Implement flush with context

[ribice]

Resolves #746

[codecov]

Codecov Report

Attention: Patch coverage is 67.64706% with 11 lines in your changes missing coverage. Please review.

Project coverage is 85.33%. Comparing base (c340089) to head (424fe5e).

Files with missing lines	Patch %	Lines
transport.go	62.50%	6 Missing ⚠️
hub.go	57.14%	2 Missing and 1 partial ⚠️
logrus/logrusentry.go	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #935      +/-   ##
==========================================
- Coverage   85.47%   85.33%   -0.15%     
==========================================
  Files          55       55              
  Lines        5486     5515      +29     
==========================================
+ Hits         4689     4706      +17     
- Misses        653      663      +10     
- Partials      144      146       +2     

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[ribice]

The only thing failing here is the coverage. Do I have to 'fix' it or we can merge as-is?

[cleptric]

Do we have docs for this?

[ribice]

Do we have docs for this?

No. Should I add it in sentry-docs?

[cleptric]

Yes

[ribice]

@cleptric getsentry/sentry-docs#12308