refactor: use yarn workspaces for easier install

the goal: when someone clones this repo and runs `yarn` to install
dependencies, all of the dependencies for the templates get installed as
well. Additionally, this is done in such a way that linting works for
these projects.

This is a little bit tricky! Each template has a file at
`assembly/tsconfig.json` which has an `extends` directive. This
`extends` points to `../node_modules/assemblyscript/[...]`. So the
installation of packages for each of these templates must be done in
such a way that this relative lookup does not break. That's what the
`nohoist` option does.

Note that typescript supports some version of module resolution, rather
than relative path, for the `extends` option. I tried to use this
briefly and ran into problems, whereas `nohoist` worked very quickly. It
seems like other people have had problems with `extends` pointing to
packages as well:
microsoft/TypeScript#18865 (comment)

This also adds the `yarn.lock`, since we have no config preventing it,
and this is considered best practice
(https://classic.yarnpkg.com/blog/2016/11/24/lockfiles-for-all/)

package.json

@@ -115,5 +115,10 @@
     "webpack-cli": "^3.3.4",
     "webpack-dev-server": "^3.7.1",
     "webpackbar": "^4.0.0"
+  },
+  "private": true,
+  "workspaces": {
+    "packages": [ "templates/*" ],
+    "nohoist": [ "**/assemblyscript" ]
   }
 }

templates/02-counter/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "@wasm/token_contract_ts",
+  "name": "@wasm/counter_ts",
   "description": "",
   "version": "0.0.1",
   "scripts": {