[ADF-2134] App config schema (#2892)

* Application config schema

* Adding descriptions

* validate-config npm script

* Finishing schema

* Package.json modifications

* Add validation to demo shell start

demo-shell/package.json

@@ -5,6 +5,7 @@
   "author": "Alfresco Software, Ltd.",
   "scripts": {
     "ng": "ng",
+    "prestart": "npm run validate-config",
     "start": "npm run server-versions && rimraf dist && ng serve --host 0.0.0.0 --app dist --open --aot=false",
     "start:dev": "npm run lint && npm run server-versions && rimraf dist && npm run clean-lib-angular && concurrently \"ng serve --host 0.0.0.0 --disable-host-check --app dev pp-dev --proxy-config proxy.conf.js --open\" \"npm run style:dev -- --watch\" ",
     "start:dist": "npm run server-versions && rimraf dist && node --max_old_space_size=30000 node_modules/.bin/ng serve --prod --build-optimizer=false  --aot=false --host 0.0.0.0 --disable-host-check --app dist",
@@ -15,6 +16,7 @@
     "test": "ng test",
     "lint": "ng lint",
     "e2e": "ng e2e",
+    "validate-config": "ajv validate -s ../lib/core/app-config/schema.json -d ./src/app.config.json --errors=text --verbose",
     "server-versions": "rimraf ./src/versions.json && npm list --depth=0 --json=true --prod=true > ./src/versions.json  || exit 0",
     "clean": "npm run clean-build  && rimraf dist node_modules typings dist",
     "clean-lib-angular": "rimraf ../lib/node_modules/@angular",
@@ -105,6 +107,7 @@
     "@types/jasmine": "~2.5.53",
     "@types/jasminewd2": "~2.0.2",
     "@types/node": "~6.0.60",
+    "ajv-cli": "^3.0.0",
     "codelyzer": "4.0.0",
     "concurrently": "^3.5.1",
     "jasmine-core": "~2.6.2",

demo-shell/src/app.config.json

@@ -1,4 +1,5 @@
 {
+    "$schema": "../../lib/core/app-config/schema.json",
     "ecmHost": "http://{hostname}:{port}",
     "bpmHost": "http://{hostname}:{port}",
     "application": {