Fix newly enforce lints and clean pubspec (dart-lang/test_process#16)

- Fix `prefer_single_quotes` which is now enforced by `package:pedantic`
- Add a blank CHANGELOG section so it matches pubspec.
- Remove unused author section from pubspec.
- Simplify constraints on packages that had an unnecessarily low lower
  bound. Each of these packages doesn't support the Dart 2 stable SDK
  before their latest major version number.
- Fail travis for warnings and lints.
5 files changed
tree: 6565c759b264fd24703ceced38aa830b34b88a7b
  1. pkgs/