Release 0.20.1

# History

## 0.20.1

Install/update via the bootstrap script:

```shell
wget https://raw.githubusercontent.com/dokku/dokku/v0.20.1/bootstrap.sh
sudo DOKKU_TAG=v0.20.1 bash bootstrap.sh
```

### Bug Fixes

- #3916: @josegonzalez Change error exit to warning when no apps exist

### New Features

- #3918: @josegonzalez Upgrade herokuish to 0.5.11
- #3915: @josegonzalez Add ability to check if a plugin has been installed
- #3914: @josegonzalez Add ability to change or disable the access/error log path
- #3913: @josegonzalez Upgrade herokuish

### Documentation

- #3907: @josegonzalez Add sponsoring link to issue template
- #3904: @jazzzz Update dokku-apt entry
- #3902: @josegonzalez Remove extra commas from network docs

### Other

- #3909: @dependabot-preview[bot] chore(deps): bump werkzeug from 1.0.0 to 1.0.1 in /tests/apps/python-flask
- #3903: @dependabot-preview[bot] chore(deps-dev): bump heroku/heroku-buildpack-php from 172 to 173 in /tests/apps/php

docs/development/release-process.md

@@ -29,7 +29,7 @@ The workflow looks like this:
 ```shell
 # having dokku-arch in ../dokku-arch
 vagrant up build-arch
-# wait for "==> build-arch: ==> Finished making: dokku 0.20.0-2 (Mon Feb 22 23:20:37 CET 2016)"
+# wait for "==> build-arch: ==> Finished making: dokku 0.20.1-2 (Mon Feb 22 23:20:37 CET 2016)"
 cd ../dokku-arch
 git add PKGBUILD .SRCINFO
 git commit -m 'Update to dokku 0.9.9'