Remove author from pubspec to silence pub complaints

[jcollins-g]

A new version of pub has a new warning. This fixes:

try-publish: |       '-- pubspec.yaml
try-publish: '-- tool
try-publish:     |-- after_failure_travis.sh
try-publish:     |-- builder.dart
try-publish:     |-- doc_packages.dart
try-publish:     |-- grind.dart
try-publish:     |-- install_travis.sh
try-publish:     '-- travis.sh
try-publish: Suggestions:
try-publish: * Your pubspec.yaml includes an "author" section which is no longer used and may be removed.
try-publish:
try-publish: Package has 1 warning.
ProcessException: SubprocessLauncher got non-zero exitCode: 65

[jcollins-g]

Going to force squash and merge because of bot trouble.

[coveralls]

Coverage remained the same at 93.877% when pulling 8672854 on remove-author into 6cee315 on master.