Updating Brew Installation Instructions

* We are trying to keep the binary building on Go 1.13 to support building the project on Ubuntu 20.04 LTS
* Go 1.14+ is required to run the test suite
* We build our releases on Go 1.15

This adds a CI check that verifies that the project compiles on 1.13

Clarify our Go version requirements

A basic first pass on gh pr checks that shows all check runs for a given
PR's latest commit.

[Feature] Create repositories from a template repo

When applying metadata to the new PR such as assignees or reviewers, if
the operation fails, an error message would get printed:

    failed to create pull request: <API error text>

This was misleading, because the PR did get created; it's just that
updating it failed. The new error message is:

    https://github.com/OWNER/REPO/pull/123
    pull request update failed: <API error text>

The PR URL is printed on stdout and the error message is printed on
stderr. In case of any errors, the exit code is still non-zero.

If HTTP 422 is encountered, assume that OAuth Device Flow is unavailable
and fall back to OAuth app authorization flow.

We used to write directly to `os.Stderr`, but we first need to convert
that into a colorable stream.

Be transparent about which part of `pr create` flow failed

properly check for tty when in powershell

Remove non-existant option: -u

Add apt update

Currently the mimecap package is an requirement to pass the test suite,
as we need /etc/mime.types to recognize the tar extension. A better idea
is to inline all of the basic test cases for the test suite.

Signed-off-by: Morten Linderud <[email protected]>

shared/upload: Add .tar format

Update install_linux.md

Added kiss linux install instructions

The `gist` command allows doing other operations than
`create`(like `edit`, `view`, etc).  So I think that `manage`
is more appropriate to the description.

Fix short description of `gist`

Fix typo overriden -> overridden

Update command-line-syntax.md

Fix typo in install_linux.md

support more ubuntus

Added option to specify branch in gh repo view

Installation Guide on Linux