Adds support for Gitpod.io (#9727)

* Adds support for Gitpod

* Adds Gitpod Dockerfile

* Adds Gitpod prebuild configuration

* Adds Theia tasks file (for use with Gitpod)

* Revert "Adds Gitpod Dockerfile"

This reverts commit bf2d76fdc057d3d05972f6d7f8e1b0c61476c2b7.

* Fixes broken json in Theia tasks file

.gitpod.yml

@@ -0,0 +1,16 @@
+tasks:
+  - init: gem install bundler -v 2.0.1
+  - init: bundle install
+ports:
+  - port: 4000
+    onOpen: open-browser
+github:
+  prebuilds:
+    master: true
+    branches: true
+    pullRequests: true
+    pullRequestsFromForks: true
+    addCheck: true
+    addComment: false
+    addBadge: true
+    addLabel: false

.theia/tasks.json

@@ -0,0 +1,30 @@
+{
+    "tasks": [
+        {
+            "label": "Generate",
+            "type": "shell",
+            "command": "bundle",
+            "args": [
+                "exec",
+                "rake",
+                "generate"
+            ],
+            "options": {
+                "cwd": "${workspaceFolder}"
+            }        
+        },
+        {
+            "label": "Preview",
+            "type": "shell",
+            "command": "bundle",
+            "args": [
+                "exec",
+                "rake",
+                "preview"
+            ],
+            "options": {
+                "cwd": "${workspaceFolder}"
+            }        
+        }
+    ]
+}