Drop explicit Heroku support

Heroku is no longer offering free tier where you could test
ActiveWorkflow. You can still run it on heroku, but that would involve
setting up individual dynos (refer to docker-compose.yml).

You can still run ActiveWorkflow on heroku

Author: Vidas P

CHANGELOG.md

@@ -6,13 +6,19 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [current]
+### Removed
+- Heroku-specific support (single button install, custom docker image, etc)
+
+### Fixed
+- Post agent will now interpret server responses as UTF-8 with an option
+  to override.
 
 ## [0.9.15.1] - 2021-11-04
 ### Added
 - SECURITY.md
 
 ## [0.9.15] - 2021-08-04
-## Removed
+### Removed
 - Removed IMAP Folder agent.
 - Removed FTP Site agent.
 

Dockerfile.heroku

@@ -6,9 +6,6 @@ start:
 build-image:
 	docker build -t local/active_workflow .
 
-HEROKU_APP = $(shell heroku apps:info | grep 'Web URL' | awk -F'[/.]' '{print $$3}')
-HEROKU_CONTAINER = registry.heroku.com/${HEROKU_APP}/web
-
 .PHONY: test
 test:
 	bundle exec rspec spec

Makefile

@@ -55,18 +55,6 @@ docker run -p 3000:3000 --rm automaticmode/active_workflow
 
 Once it starts you can login at `http://localhost:3000` with `admin`/`password`.
 
-### Try it on Heroku
-
-Another quick and easy way to check out ActiveWorkflow is by deploying it on
-[Heroku](https://www.heroku.com/).
-
-All you need to do is click the button bellow and fill in the environment variables for your seed user (admin):
-`SEED_USERNAME`, `SEED_PASSWORD` (must be at least 8 characters long) and `SEED_EMAIL`.
-
-[![Deploy](https://www.herokucdn.com/deploy/button.svg)](https://heroku.com/deploy?template=https://github.com/automaticmode/active_workflow&env[SINGLE_DYNO]=1)
-
-*Note: this configuration is not recommended for production, please see [Getting Started - Running on Heroku](https://docs.activeworkflow.org/#running-on-heroku) for more details.*
-
 ## Documentation
 
 You can find the full project documentation at [docs.activeworkflow.org](https://docs.activeworkflow.org/).