Check connection status

[jhecking]

Check whether server connections are alive before returning them from the connection pool. If the server closed the connection, e.g. due to proto-fd-idle-ms limit being reached, the connection is removed from the pool and, if necessary, a new connection is established.

If the server is hard killed, or the connection is closed for other reasons, it may not be possible for the client to detect this, and an Aerospike::Exception::Connection error may still be raised.

Resolves #67.

[codecov-io]

Codecov Report

Merging #72 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #72      +/-   ##
==========================================
- Coverage   95.59%   95.59%   -0.01%     
==========================================
  Files         153      155       +2     
  Lines        9974    10054      +80     
==========================================
+ Hits         9535     9611      +76     
- Misses        439      443       +4

Impacted Files	Coverage Δ
lib/aerospike/key.rb	100% <ø> (ø)	⬆️
lib/aerospike/utils/packer.rb	100% <100%> (ø)	⬆️
lib/aerospike/utils/unpacker.rb	100% <100%> (ø)	⬆️
lib/aerospike.rb	100% <100%> (ø)	⬆️
lib/aerospike/utils/buffer.rb	95.08% <100%> (ø)	⬆️
lib/aerospike/utils/connection_pool.rb	100% <100%> (ø)
spec/aerospike/util/connection_pool_spec.rb	100% <100%> (ø)
lib/aerospike/socket/base.rb	87.5% <100%> (+0.46%)	⬆️
lib/aerospike/node.rb	100% <100%> (ø)	⬆️
lib/aerospike/cluster.rb	93.4% <100%> (-0.22%)	⬇️
... and 6 more

---

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