tests: Switch from Travis to Github Actions

Travis placed an unnecessary breaking restriction on our tests and failed to respond within 72 hours to our complaint.  This has forced us to introduce Github Actions to manage our testing.  This is hopefully a temporary measure while Travis either gets itself together or we find a non-Github requirement.

.github/workflows/rate-limit.yml

@@ -0,0 +1,39 @@
+name: "rate limit"
+
+# any branch is useful for testing before a PR is submitted
+on: [push, pull_request]
+
+jobs:
+  ratelimit:
+    # run on pushes to any branch
+    # run on PRs from external forks
+    if: |
+         (github.event_name != 'pull_request')
+         || (github.event.pull_request.head.repo.id != github.event.pull_request.base.repo.id)
+    name: test
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    - name: docker network
+      run: docker network create --subnet=172.23.42.0/16 ep_net
+
+    - name: build docker image
+      run: |
+        docker build -f Dockerfile -t epl-debian-slim .
+        docker build -f tests/ratelimit/Dockerfile.nginx -t nginx-latest .
+        docker build -f tests/ratelimit/Dockerfile.anotherip -t anotherip .
+    - name: run docker images
+      run: |
+        docker run --name etherpad-docker -p 9000:9001 --rm --network ep_net --ip 172.23.42.2 -e 'TRUST_PROXY=true' epl-debian-slim &
+        docker run -p 8081:80 --rm --network ep_net --ip 172.23.42.1 -d nginx-latest
+        docker run --rm --network ep_net --ip 172.23.42.3 --name anotherip -dt anotherip
+
+    - name: install dependencies and create symlink for ep_etherpad-lite
+      run: bin/installDeps.sh
+
+    - name: run rate limit test
+      run: |
+        cd tests/ratelimit
+        ./testlimits.sh