port forwards over SSH

[rberrelleza]

option to use SSH forward instead of port-forward for the forward ports.

[derek]

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[derek]

Thank you for your contribution. I've just checked and your Pull Request doesn't appear to have any description.
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[golangcibot]

Error return value of io.WriteString is not checked (from errcheck)

[codecov]

Codecov Report

Merging #755 into master will increase coverage by 1.38%.
The diff coverage is 53.15%.

@@            Coverage Diff             @@
##           master     #755      +/-   ##
==========================================
+ Coverage   30.59%   31.98%   +1.38%     
==========================================
  Files          59       62       +3     
  Lines        4677     4821     +144     
==========================================
+ Hits         1431     1542     +111     
- Misses       3148     3159      +11     
- Partials       98      120      +22

Impacted Files	Coverage Δ
pkg/syncthing/syncthing.go	0.57% <ø> (ø)	⬆️
cmd/up.go	0% <0%> (ø)	⬆️
pkg/k8s/forward/manager.go	31.38% <0%> (-0.47%)	⬇️
pkg/model/dev.go	64.66% <20%> (-1.01%)	⬇️
pkg/ssh/pool.go	54.16% <54.16%> (ø)
pkg/ssh/forward.go	71.42% <71.42%> (ø)
pkg/ssh/manager.go	72.09% <72.09%> (ø)
pkg/ssh/reverse.go	72.72% <73.17%> (+61.78%)	⬆️
... and 2 more

---

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