Add testing/README.md, rename test/ to spec/, canonicalize indentation to 2 spaces.

Author: Robert-Jan Huijsman

.npmignore

@@ -3,4 +3,4 @@ coverage
 .vscode
 
 # The SDK's internal unit tests might confuse users looking for the testing/ module.
-test
+spec

package.json

@@ -6,9 +6,9 @@
   "scripts": {
     "build": "node_modules/.bin/tsc",
     "build:pack": "npm prune --production && npm install typescript && node_modules/.bin/tsc && npm pack && npm install",
-    "lint": "node_modules/.bin/tslint src/{**/*,*}.ts test/{**/*,*}.ts",
-    "pretest": "node_modules/.bin/tsc test/index.spec.ts --target es5 --outDir .tmp && cp -r test/fixtures .tmp/test",
-    "test": "npm run lint && mocha .tmp/test/index.spec.js",
+    "lint": "node_modules/.bin/tslint src/{**/*,*}.ts spec/{**/*,*}.ts",
+    "pretest": "node_modules/.bin/tsc spec/index.spec.ts --target es5 --outDir .tmp && cp -r spec/fixtures .tmp/spec",
+    "test": "npm run lint && mocha .tmp/spec/index.spec.js",
     "posttest": "rm -rf .tmp"
   },
   "repository": {