close second goroutine in raft-net

fix up linting

add tests for TLSConfig object

code review feedback

Revert "close raft long-lived connections"

This reverts commit 3ffda28206fcb3d63ad117fd1d27ae6f832b6625.

reload raft connections on changing tls

add locks around changing server configuration

Fix detection of successful batch allocations

This PR restores older behavior of detecting successful batch
allocations (04d86ffd). This has the
side effect that we correctly filter desired status stop but not
successful batch allocations and create their replacements.

Add missing -group=cache to docs

Prevent absolute URLs in checks paths

Fixes #3699

Merges recent work from 0.8 branch

Make macos/osx builds optional in Travis

securing guide: small signal typo and argument consistency