AppVeyor

[mrpalide]

Did you run make format && make check? Yes

Fixes #812

Changes:

• Add .appveyor.yml file for AppVeyor CI service to test, build and release.

How to test this

• For test and build, just make account on AppVeyor, make project for repo, and push commits.
• For release, you should push a tag. You need add your <secure_code> in line 150 and line 113. To create that, first create Personal access tokens in Settings -> Developers Settings on GitHub setting. Then secure this token at your Account -> Encrypt YAML tab in your AppVeyor dashboard. [link].

[CLAassistant]

All committers have signed the CLA.

[mrpalide]

Some problems:

1. Latest go version for macos image on AppVeyor is 1.15, some build-in packages same as is/fs and embed available since v1.16 .
2. The windows related codes has some problem.

[mrpalide]

Updates:

• MacOS build now complete with installing go1.16 manually

Problems:

• The Windows build get failed because of problems in related codes.
• checksum.txt cannot create automaticaly by AppVeyor same as GoReleaser

Question:

• I see multiple goarm variables on .goreleaser.yml, why use multiple goarm values, and which one is used in the build? I set GOARM=7.

[alexadhy]

Updates:

* MacOS build now complete with installing go1.16 manually

Problems:

* The Windows build get failed because of problems in related codes.

* `checksum.txt` cannot create automaticaly by **AppVeyor** same as **GoReleaser**

Question:

* I see multiple `goarm` variables on [`.goreleaser.yml`](https://github.com/skycoin/skywire/blob/aa0aa83b21d7b9e15c90d397c711e732980b52c6/.goreleaser.yml#L28), why use multiple `goarm` values, and which one is used in the build? I set `GOARM=7`.

• windows build will have to wait for Feature/windows pty dmsg#93
• goreleaser goarm, I think it's because we produce both ARMv7 and ARMv6 binaries, not sure why it's necessary.

[ersonp]

We need ARMv7 and ARMv6 binaries as we are supporting them in skybian (develop) here and here.

[jdknives]

@mrpalide can you please make another commit to check if the integration runs?