feat: use keep alive agents for all fragment requests

[vigneshshanmugam]

• part of 4.0.0 Release #274
• Merge chore: Drop node 6 support, add 10 & 11 to travis #283 and rerun this test.

[codecov]

Codecov Report

Merging #282 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #282      +/-   ##
==========================================
+ Coverage   99.55%   99.56%   +<.01%     
==========================================
  Files          17       19       +2     
  Lines         670      684      +14     
  Branches      127      128       +1     
==========================================
+ Hits          667      681      +14     
  Misses          3        3

Impacted Files	Coverage Δ
lib/agent-store.js	100% <100%> (ø)
lib/constants.js	100% <100%> (ø)
lib/request-fragment.js	100% <100%> (ø)	⬆️

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[ruiaraujo]

The socket ttl should be configurable

[vigneshshanmugam]

Hmmm, I was thinking the same as well, Plus have to come up with custom config options for circuit breaker pool settings + metrics + caching of fragments..

I will come up with some proposal.

[vigneshshanmugam]

Thought for a while about this and I think we can customize all of the logic in a client library like perron(or create one specific for tailor - or give PR to perron to make it work). Perron already supports circuit breaker logic for clients and we can easy add cache specific logic as well..

I will give PR to perron once i have sometime to work on some features.