Add EmailEngine app (#676)

* Add EmailEngine app

* Add EmailEngine logo

* Remove `--reguirepass` flag for Redis instance

* Update yml build file

* Apply Prettier style to emailengine.yml

public/v4/apps/emailengine.yml

@@ -0,0 +1,44 @@
+captainVersion: 4
+services:
+    # EmailEngine
+    $$cap_appname:
+        depends_on:
+            - $$cap_appname-redis
+        image: andris9/emailengine:$$cap_emailengine_version
+        restart: always
+        environment:
+            WAIT_HOSTS: srv-captain--$$cap_appname-redis:6379
+            EENGINE_REDIS: redis://:@srv-captain--$$cap_appname-redis:6379
+        caproverExtra:
+            containerHttpPort: '3000'
+    # Redis
+    $$cap_appname-redis:
+        image: redis:$$cap_redis_version
+        command: redis-server
+        volumes:
+            - $$cap_appname-db-data:/data/db
+        restart: always
+        caproverExtra:
+            notExposeAsWebApp: 'true'
+caproverOneClickApp:
+    variables:
+        - id: $$cap_emailengine_version
+          label: EmailEngine Version
+          defaultValue: 'v2'
+          description: Check out their docker page for the valid tags https://hub.docker.com/r/andris9/emailengine/tags
+          validRegex: /^([^\s^\/])+$/
+        - id: $$cap_redis_version
+          label: Redis Version
+          defaultValue: '7.0.2'
+          description: Check out their docker page for the valid tags https://hub.docker.com/_/redis?tab=tags
+          validRegex: /^([^\s^\/])+$/
+    instructions:
+        start: >-
+            IMAP and SMTP are hard, so let EmailEngine handle these for you. Run REST API calls to interact with email servers and receive webhooks for changes on tracked email accounts. With EmailEngine, you can focus on building features that matter instead of spending time rolling custom IMAP and SMTP connectivity logic.
+        end: >-
+            You're done! 🤗
+            Your EmailEngine is available at http://$$cap_appname.$$cap_root_domain:3000
+    displayName: 'EmailEngine'
+    isOfficial: true
+    description: Self-hosted application that opens a permanent IMAP connection against every registered email account to translate API requests to IMAP commands and monitor changes on these accounts.
+    documentation: Taken from https://hub.docker.com/r/andris9/emailengine