buildifier lint presubmit changes.

- Enable checks for rule-impl-return.
- Use the new bazelci support to disable the warnings current giving false positives.
- Remove travis configuration since bazelci now supports everything.

RELNOTES: None
PiperOrigin-RevId: 237260583

.bazelci/presubmit.yml

@@ -62,4 +62,9 @@ tasks:
       - "//examples/..."
       - "-//examples/apple/..."
 
-buildifier: latest
+buildifier:
+  version: latest
+  # uninitialized has issues:
+  # - https://github.com/bazelbuild/buildtools/issues/549
+  # - https://github.com/bazelbuild/buildtools/issues/550
+  warnings: -uninitialized

.travis/build.sh

@@ -51,10 +51,7 @@ if [[ -n "${BUILDIFIER:-}" ]]; then
     # uninitialized has issues:
     # - https://github.com/bazelbuild/buildtools/issues/549
     # - https://github.com/bazelbuild/buildtools/issues/550
-    # rule-impl-return doesn't deal well with having to return
-    #   legacy style, work being done to help with this, just
-    #   not ready yet.
-    --warnings=-rule-impl-return,-uninitialized
+    --warnings=-uninitialized
   )
 
   # Check for lint issues?

README.md

@@ -1,6 +1,5 @@
 # Swift Rules for [Bazel](https://bazel.build)
 
-[![Build Status](https://travis-ci.org/bazelbuild/rules_swift.svg?branch=master)](https://travis-ci.org/bazelbuild/rules_swift)
 [![Build status](https://badge.buildkite.com/d562b11425e192a8f6ba9c43715bc8364985bccf54e4b9194a.svg)](https://buildkite.com/bazel/rules-swift-swift)
 
 This repository contains rules for [Bazel](https://bazel.build) that can be