New tool to store SQL connection configs locally (#218)

* added a new tool to store SQL connections locally. Modified the peek definition tests to create test database before running test


* fixed failing test QueryExecutionPlanInvalidParamsTest

* Fixes based on code review comments

* fixed failing test GetSignatureHelpReturnsNotNullIfParseInfoInitialized

test/Microsoft.SqlTools.ServiceLayer.TestEnvConfig/project.json

@@ -0,0 +1,25 @@
+{
+  "version": "1.0.0-*",
+  "buildOptions": {
+    "emitEntryPoint": true
+  },
+
+  "dependencies": {
+    "Microsoft.SqlTools.ServiceLayer.Test.Common": "1.0.0-*"
+  },
+  "testRunner": "xunit",
+  "frameworks": {
+    "netcoreapp1.0": {
+      "dependencies": {
+        "Microsoft.NETCore.App": {
+          "type": "platform",
+          "version": "1.0.0"
+        }
+      },
+      "imports": [
+        "dotnet5.4",
+        "portable-net451+win8"
+      ]
+    }
+  }
+}