Remove appveyor config, Travis CI for windows now seems to work

.appveyor.yml

@@ -1,42 +0,0 @@
-version: '{build}'
-
-branches:
-  only:
-  - master
-  - /^v[0-9.]+\.[0-9.]+/
-
-cache:
-  - '%USERPROFILE%\.cargo'
-  - '%APPVEYOR_BUILD_FOLDER%\target'
-
-clone_folder: d:\projects\solana
-
-build_script:
-  - bash ci/publish-tarball.sh
-
-notifications:
-  - provider: Slack
-    incoming_webhook:
-      secure: GJsBey+F5apAtUm86MHVJ68Uqa6WN1SImcuIc4TsTZrDhA8K1QWUNw9FFQPybUWDyOcS5dly3kubnUqlGt9ux6Ad2efsfRIQYWv0tOVXKeY=
-    channel: ci-status
-    on_build_success: false
-    on_build_failure: true
-    on_build_status_changed: true
-
-deploy:
-  - provider: S3
-    access_key_id:
-      secure: fTbJl6JpFebR40J7cOWZ2mXBa3kIvEiXgzxAj6L3N7A=
-    secret_access_key:
-      secure: vItsBXb2rEFLvkWtVn/Rcxu5a5+2EwC+b7GsA0waJy9hXh6XuBAD0lnHd9re3g/4
-    bucket: release.solana.com
-    region: us-west-1
-    set_public: true
-
-  - provider: GitHub
-    auth_token:
-      secure: 81fEmPZ0cV1wLtNuUrcmtgxKF6ROQF1+/ft5m+fHX21z6PoeCbaNo8cTyLioWBj7
-    draft: false
-    prerelease: false
-    on:
-      appveyor_repo_tag: true