normalized connection properties

[msimerson]

this is a prequel to #1547

It includes just the changes in connection.js, as shrewdly suggested by @smfreegard, as well as using .set() more often as commented by @baudehlo.

• converts connection.remote_* to connection.remote.*
• converts connection.local_* to connection.local.*
• converts connection.using_tls -> connection.tls.enabled
• maintains previous names, providing backwards compatibility

[codecov-io]

Current coverage is 35.86% (diff: 25.71%)

Merging #1577 into master will increase coverage by 0.02%

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