feat(jaeger-exporter): adds flushing on an interval

[bg451]

closes open-telemetry#340

Which problem is this PR solving?

Short description of the changes

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This change is 

[codecov-io]

Codecov Report

Merging #11 into master will decrease coverage by 0.11%.
The diff coverage is 62.5%.

@@            Coverage Diff             @@
##           master      #11      +/-   ##
==========================================
- Coverage   97.85%   97.74%   -0.12%     
==========================================
  Files         104      104              
  Lines        4859     4871      +12     
  Branches      421      420       -1     
==========================================
+ Hits         4755     4761       +6     
- Misses        104      110       +6

Impacted Files	Coverage Δ
...ackages/opentelemetry-exporter-jaeger/src/types.ts	100% <ø> (ø)	⬆️
...ckages/opentelemetry-exporter-jaeger/src/jaeger.ts	85.71% <62.5%> (-5.47%)	⬇️
...-plugin-http/test/functionals/http-package.test.ts	93.93% <0%> (-4.55%)	⬇️
...entelemetry-exporter-jaeger/test/transform.test.ts	100% <0%> (ø)	⬆️
...telemetry-plugin-grpc/test/utils/assertionUtils.ts	100% <0%> (ø)	⬆️
...pe-async-hooks/test/AsyncHooksScopeManager.test.ts	100% <0%> (ø)	⬆️
.../opentelemetry-exporter-jaeger/test/jaeger.test.ts	100% <0%> (ø)	⬆️