use node 10.13.0

Revert "enable experimentalFeatures.canonicalURLRedirect by default"

This reverts commit 4ffb62c, which caused sourcegraph/sourcegraph#807.

Use correct repository search path for github enterprise (sourcegraph…

…#985)

Reduce the number of aws code commit repos fetched per api call from …

…50 to 25 (sourcegraph#857)

Use git wire protocol v2 (sourcegraph#757)

add authz.Provider.Validate method

frontend: correct docker:cmd directive form

`serve` is treated as a shell form and hence runs:

```
/sbin/tini -- /usr/local/bin/frontend /bin/sh -c serve
```

Which is incorrect. Instead, we want `["serve"]` which is treated as parameters
to `ENTRYPOINT` by Docker, i.e.:

```
/sbin/tini -- /usr/local/bin/frontend serve
```

frontend: specify default serve command arg

So that we do not need to specify it as part of deployment, i.e. we can remove:

https://github.com/sourcegraph/deploy-sourcegraph/blob/0cbd3d084f97ad8f984d307e7d85f0f8983bd5cb/base/frontend/sourcegraph-frontend.Deployment.yaml#L28

searcher: correctly use background context

fetch SRC_GIT_SERVERS from frontend if not configured (sourcegraph#616)

* pkg/gitserver: refactor address fetching for client (no functionality change)

* httpapi: add method for fetching SRC_GIT_SERVERS from frontend

* cmd/searcher: refactor MaxConcurrentFetchTar to be mutable at runtime

* pkg/gitserver: if SRC_GIT_SERVERS is not set, fetch from frontend

* fix closing of AddrsReady channel

* frontend: always use localhost for InternalClient URL

* use atomic.Value

* fix import

* properly update SetMaxConcurrentFetchTar at runtime

* localhost -> 127.0.0.1

* use sync.Once

* fix gitserverAddrList default value

* ensure error for division by zero is always clear

* ensure we wait for one successful gitserver address fetch first

* set default SRC_GIT_SERVERS when testing