Feat/model backed ui (#1145)

This is an initial PR for a new model-driven UI where extensions can provide definitions of the components & how they're laid out using Containers.
#1140, #1141, #1142, #1143 and #1144 are all tracking additional work needed to improve the initial implementation and fix some issues with the implementation.

Features:
- Supports defining a FlexContainer that maps to a flexbox-based layout.
- Supports creating a card component, which is a key-value pair based control that will lay out simple information to a user. Eventually this will have an optional set of actions associated with it.
- Has a sample project which shows how to use the API and was used for verification

samples/sqlservices/package.json

@@ -0,0 +1,81 @@
+{
+    "name": "sqlservices",
+    "displayName": "sqlservices",
+    "description": "Lists SQL Server service status in the management dashboard for a server",
+    "version": "0.0.1",
+    "publisher": "demo",
+    "engines": {
+        "vscode": "^1.21.0",
+        "sqlops": "*"
+    },
+    "categories": [
+        "Other"
+    ],
+    "activationEvents": [
+        "*"
+    ],
+    "main": "./out/src/extension",
+    "contributes": {
+        "dashboard.tabs": [
+            {
+                "id": "sqlservices.tab",
+                "title": "sqlservices",
+                "icon": {
+                    "light": "./out/src/media/insights.svg",
+                    "dark": "./out/src/media/insights_inverse.svg"
+                },
+                "description": "Shows available services running in the SQL Server instance",
+                "container": {
+                    "nav-section": [
+                        {
+                            "id": "sqlservices",
+                            "title": "Services",
+                            "gridItemConfig": {
+                                "sizex": 2,
+                                "sizey": 1
+                            },
+                            "container": {
+                                "modelview-container": null
+                            }
+                        },
+                        {
+                            "id": "splitPanel",
+                            "title": "SplitPanel",
+                            "gridItemConfig": {
+                                "sizex": 2,
+                                "sizey": 1
+                            },
+                            "container": {
+                                "modelview-container": null
+                            }
+                        }
+                    ]
+                }
+            }
+        ]
+    },
+    "scripts": {
+        "build": "gulp build",
+        "compile": "gulp compile",
+        "watch": "gulp watch",
+        "typings": "gulp copytypings",
+        "postinstall": "node ./node_modules/vscode/bin/install && node ./node_modules/sqlops/bin/install"
+    },
+    "dependencies": {
+        "vscode-nls": "^3.2.2"
+    },
+    "devDependencies": {
+        "@types/node": "^7.0.43",
+        "child-process-promise": "^2.2.1",
+        "del": "^3.0.0",
+        "gulp": "^4.0.0",
+        "gulp-color": "0.0.1",
+        "gulp-sourcemaps": "^2.6.4",
+        "gulp-tslint": "^6.0.2",
+        "gulp-typescript": "^3.2.4",
+        "sqlops": "github:anthonydresser/sqlops-extension-sqlops",
+        "tslint": "^3.14.0",
+        "typescript": "^2.6.1",
+        "vscode": "^1.1.14"
+    }
+}