Add support for Gitaly feature flags

See merge request gitlab-org/gitlab-shell!351

gitaly#1846

Gitaly does not store or remember feature flags. We must pass them in as
metadata on each request. This MR adds plumbing to pass Gitaly feature flags
supplied by gitlab-rails to the Gitaly server as gRPC request metadata.
Signed-off-by: Mateusz Nowotyński <maxmati4@gmail.com>

Make console messages consistent

See merge request gitlab-org/gitlab-shell!334

Move Go code up one level

See merge request gitlab-org/gitlab-shell!350

Remove handler functions which aren't used

See merge request gitlab-org/gitlab-shell!349

Release v10.2.0

See merge request gitlab-org/gitlab-shell!348

Remove dead Ruby code and unused binaries

See merge request gitlab-org/gitlab-shell!346

Upgrade Gitaly to 1.68.0

See merge request gitlab-org/gitlab-shell!347

Gitaly 1.68.0 upgrades gRPC to 1.24.0

Remove ruby tag from .gitlab-ci.yml

See merge request gitlab-org/gitlab-shell!345

Version 10.1.0

See merge request gitlab-org/gitlab-shell!344

Remove buildCheckAllowedEnv() test helper

Closes #215

See merge request gitlab-org/gitlab-shell!343

Rewrite `bin/check` in Go

See merge request gitlab-org/gitlab-shell!341

Decouple `bin/compile` and `bin/install` from code in `lib/`

See merge request gitlab-org/gitlab-shell!340

Remove deprecated create-hooks script

See merge request gitlab-org/gitlab-shell!342

This commit duplicates a small amount of Ruby code that is run at build
or install time. Over time, it would be nice to remove the dependency
on Ruby for these steps, but the focus right now is on run-time.

We'll be removing lib/* from gitlab-shell very soon, and these commands
need to keep working when we do.

Extend group IP restriction to Git activity

See merge request gitlab-org/gitlab-shell!335