Setup gitpod (CosmWasm#79)

* Setup gitpod

* Enable rust

* Add to readme

.gitpod.Dockerfile

@@ -0,0 +1,17 @@
+### wasmd ###
+FROM cosmwasm/wasmd:v0.18.0 as wasmd
+
+### rust-optimizer ###
+FROM cosmwasm/rust-optimizer:0.11.5 as rust-optimizer
+
+FROM gitpod/workspace-full:latest
+
+COPY --from=wasmd /usr/bin/wasmd /usr/local/bin/wasmd
+COPY --from=wasmd /opt/* /opt/
+
+RUN sudo apt-get update \
+    && sudo apt-get install -y jq \
+    && sudo rm -rf /var/lib/apt/lists/*
+
+RUN rustup update stable \
+   && rustup target add wasm32-unknown-unknown

.gitpod.yml

@@ -0,0 +1,11 @@
+image:
+  file: .gitpod.Dockerfile
+
+vscode:
+  extensions:
+    - rust-lang.rust
+
+tasks:
+  - name: Dependencies & Build
+    init: |
+      cargo build

README.md

@@ -92,3 +92,8 @@ that have been published.
 Please replace this README file with information about your specific project. You can keep
 the `Developing.md` and `Publishing.md` files as useful referenced, but please set some
 proper description in the README.
+
+## Gitpod integration
+
+[Gitpod](https://www.gitpod.io/) container-based development platform will be enabled on your project by default.
+Follow [Gitpod Getting Started](https://www.gitpod.io/docs/getting-started) launch your workspace.