Add JSON/YAML components (#267)

Add CodeMirrorInput and VariablesField

Add components for syntax highlighting, YAML/JSON toggle

package.json

@@ -23,6 +23,7 @@
     "@babel/preset-react": "^7.0.0",
     "@lingui/cli": "^2.7.4",
     "@lingui/macro": "^2.7.2",
+    "@nteract/mockument": "^1.0.4",
     "babel-core": "^7.0.0-bridge.0",
     "babel-eslint": "^10.0.1",
     "babel-jest": "^24.7.1",
@@ -56,9 +57,12 @@
     "@patternfly/react-icons": "^3.7.5",
     "@patternfly/react-tokens": "^2.3.3",
     "axios": "^0.18.0",
+    "codemirror": "^5.47.0",
     "formik": "^1.5.1",
+    "js-yaml": "^3.13.1",
     "prop-types": "^15.6.2",
     "react": "^16.4.1",
+    "react-codemirror2": "^6.0.0",
     "react-dom": "^16.4.1",
     "react-router-dom": "^4.3.1",
     "styled-components": "^4.2.0"