Fixup the docker setup. (apple#196)

docker/Dockerfile

@@ -1,6 +1,7 @@
 ARG swift_version=5.0
 ARG ubuntu_version=bionic
-FROM swift:$swift_version-$ubuntu_version
+ARG base_image=swift:$swift_version-$ubuntu_version
+FROM $base_image
 # needed to do again after FROM due to docker limitation
 ARG swift_version
 ARG ubuntu_version

docker/docker-compose.1804.52.yaml

@@ -0,0 +1,37 @@
+version: "3"
+
+services:
+
+  runtime-setup:
+    image: swift-nio-http2:18.04-5.2
+    build:
+      args:
+        ubuntu_version: "bionic"
+        swift_version: "5.2"
+        h2spec_version: "2.2.1"
+
+  unit-tests:
+    image: swift-nio-http2:18.04-5.2
+
+  integration-tests:
+    image: swift-nio-http2:18.04-5.2
+    environment:
+      - MAX_ALLOCS_ALLOWED_create_client_stream_channel=72010
+      - MAX_ALLOCS_ALLOWED_hpack_decoding=5050
+      - MAX_ALLOCS_ALLOWED_client_server_request_response=384810
+
+  performance-test:
+    image: swift-nio-http2:18.04-5.2
+
+  h2spec:
+    image: swift-nio-http2:18.04-5.2
+
+  test:
+    image: swift-nio-http2:18.04-5.2
+    environment:
+      - MAX_ALLOCS_ALLOWED_create_client_stream_channel=72010
+      - MAX_ALLOCS_ALLOWED_hpack_decoding=5050
+      - MAX_ALLOCS_ALLOWED_client_server_request_response=384810
+
+  shell:
+    image: swift-nio-http2:18.04-5.2

docker/docker-compose.1804.53.yaml

@@ -0,0 +1,36 @@
+version: "3"
+
+services:
+
+  runtime-setup:
+    image: swift-nio-http2:18.04-5.3
+    build:
+      args:
+        base_image: "swiftlang/swift:nightly-master-bionic"
+        h2spec_version: "2.2.1"
+
+  unit-tests:
+    image: swift-nio-http2:18.04-5.3
+
+  integration-tests:
+    image: swift-nio-http2:18.04-5.3
+    environment:
+      - MAX_ALLOCS_ALLOWED_create_client_stream_channel=72010
+      - MAX_ALLOCS_ALLOWED_hpack_decoding=5050
+      - MAX_ALLOCS_ALLOWED_client_server_request_response=384810
+
+  performance-test:
+    image: swift-nio-http2:18.04-5.3
+
+  h2spec:
+    image: swift-nio-http2:18.04-5.3
+
+  test:
+    image: swift-nio-http2:18.04-5.3
+    environment:
+      - MAX_ALLOCS_ALLOWED_create_client_stream_channel=72010
+      - MAX_ALLOCS_ALLOWED_hpack_decoding=5050
+      - MAX_ALLOCS_ALLOWED_client_server_request_response=384810
+
+  shell:
+    image: swift-nio-http2:18.04-5.3