Run docker in privileged mode

From https://docs.docker.com/engine/reference/run/:

```
When the operator executes docker run --privileged, Docker will enable
access to all devices on the host as well as set some configuration in
AppArmor or SELinux to allow the container nearly all the same access to
the host as processes running outside containers on the host.
```

Regards https://github.com/profanity-im/profanity/issues/1294

.travis.yml

@@ -36,7 +36,7 @@ before_install:
 
 script:
   - if [ "$TRAVIS_OS_NAME" = "linux" ]; then
-    docker run -it profanity ./ci-build.sh;
+    docker run -it --privileged profanity ./ci-build.sh;
     fi
   - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
     ./ci-build.sh;