circumvention: add the tor experiment (#100)

* go.mod go.sum: update all non-probe-engine deps

For each line in the go.mod, run `go get -u -v $package` if the
line is not an indirect dependency and is not probe-engine.

Upgrading probe-engine is going to require the same spell that
is used in probe-engine to update psiphon.

* go get -v github.com/ooni/[email protected]

This just pins to the latest probe-engine but we've not manually
pinned all the other dependencieds yet.

Take care of the trivial API changes in probe-engine as well, such
that we can have a working build after this commit.

* go.mod go.sum: pin to probe-engine dependencies

Basically: remove all indirect dependencies. Merge this go.mod with
the one of probe-engine, to pin dependencies. Run `go mod tidy`.

* circumvention: add basic implementation of tor

This needs to be polished further, of course. But at least we have
now added support for running tor in the circumvention group.

* Readme.md: document how to update dependencies

* go get -v github.com/ooni/probe-engine@fcc9ee0a7afb

* go get -v github.com/ooni/probe-engine@4d254f5b2

* nettests/tor.go: implement summary test keys

Readme.md

@@ -31,6 +31,22 @@ Be sure you have golang >= 1.13. We use golang modules. Run
 to get information on the supported systems as well as to get
 instructions on how to install dependencies.
 
+## Updating dependencies
+
+1. update every direct dependency in `go.mod` except `probe-engine`
+using `go get -u -v $dependency`
+
+2. pin to the latest version of the `probe-engine` with
+`go get -v github.com/ooni/probe-engine@tag`
+
+3. remove all indirect dependencies from `go.mod` and merge the
+content of `probe-engine`'s `go.mod` into our `go.mod`
+
+4. `go mod tidy`
+
+The rationale of this procedure is that we want to pin exactly to
+a specific version of psiphon and of its dependencies.
+
 ## Releasing
 
 ```

go.mod

@@ -1,22 +1,17 @@
 module github.com/ooni/probe-cli
 
-go 1.12
+go 1.13
 
 require (
 	github.com/alecthomas/kingpin v2.2.6+incompatible
-	github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751 // indirect
-	github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d // indirect
 	github.com/apex/log v1.1.1
-	github.com/certifi/gocertifi v0.0.0-20191021191039-0944d244cd40 // indirect
-	github.com/fatih/color v1.7.0
+	github.com/certifi/gocertifi v0.0.0-20200104152315-a6d78f326758 // indirect
+	github.com/fatih/color v1.9.0
 	github.com/getsentry/raven-go v0.0.0-20190419175539-919484f041ea
-	github.com/kr/pty v1.1.8 // indirect
 	github.com/mattn/go-colorable v0.1.4
-	github.com/mattn/go-isatty v0.0.11 // indirect
-	github.com/ooni/probe-engine v0.4.0
-	github.com/pkg/errors v0.8.1
-	github.com/rubenv/sql-migrate v0.0.0-20191213152630-06338513c237
-	golang.org/x/sys v0.0.0-20191224085550-c709ea063b76 // indirect
+	github.com/ooni/probe-engine v0.5.1-0.20200127201608-4d254f5b22b4
+	github.com/pkg/errors v0.9.1
+	github.com/rubenv/sql-migrate v0.0.0-20200119084958-8794cecc920c
 	gopkg.in/AlecAivazis/survey.v1 v1.8.7
 	gopkg.in/mgo.v2 v2.0.0-20190816093944-a6b53ec6cb22 // indirect
 	upper.io/db.v3 v3.6.3+incompatible