Use yarn instead of npm for more reproducible building

Dockerfile

@@ -15,25 +15,25 @@ RUN set -x \
     && apt-get update \
     && apt-get install curl -y \
     && curl -sL https://deb.nodesource.com/setup_6.x | bash - \
-    && apt-get install git postgresql-client bzip2 gcc g++ make libpq-dev libffi-dev nodejs --no-install-recommends -y \
+    && curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - \
+    && echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list \
+    && apt-get update \
+    && apt-get install git postgresql-client bzip2 gcc g++ make \
+        libpq-dev libffi-dev nodejs yarn --no-install-recommends -y \
     && apt-get autoremove -y \
     && apt-get clean \
     && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 COPY package.json /tmp/package.json
+COPY yarn.lock /tmp/yarn.lock
 
 # Install NPM dependencies
 RUN set -x \
     && npm install -g gulp-cli
 
-# This depedency was creating issues so we install it separately
-RUN set -x \
-    && cd /tmp \
-    && npm install node-sass
-
 RUN set -x \
     && cd /tmp \
-    && npm install --loglevel http \
+    && yarn install --loglevel http \
     && mkdir /app \
     && cp -a /tmp/node_modules /app/
 

package.json

@@ -4,7 +4,7 @@
   },
   "name": "ooni-measurements",
   "version": "1.0.0-beta.3",
-  "license": "BSD",
+  "license": "BSD-2-Clause",
   "dependencies": {
     "babel-core": "6.14.0",
     "babel-loader": "6.2.5",

yarn.lock

@@ -3581,14 +3581,14 @@ sax@~1.2.1:
   version "1.2.1"
   resolved "https://registry.yarnpkg.com/sax/-/sax-1.2.1.tgz#7b8e656190b228e81a66aea748480d828cd2d37a"
 
-"semver@2 || 3 || 4 || 5", semver@~5.3.0:
-  version "5.3.0"
-  resolved "https://registry.yarnpkg.com/semver/-/semver-5.3.0.tgz#9b2ce5d3de02d17c6012ad326aa6b4d0cf54f94f"
-
-"[email protected] || 3.x || 4 || 5", semver@^4.1.0:
+"semver@2 || 3 || 4 || 5", "[email protected] || 3.x || 4 || 5", semver@^4.1.0:
   version "4.3.6"
   resolved "https://registry.yarnpkg.com/semver/-/semver-4.3.6.tgz#300bc6e0e86374f7ba61068b5b1ecd57fc6532da"
 
+semver@~5.3.0:
+  version "5.3.0"
+  resolved "https://registry.yarnpkg.com/semver/-/semver-5.3.0.tgz#9b2ce5d3de02d17c6012ad326aa6b4d0cf54f94f"
+
 sequencify@~0.0.7:
   version "0.0.7"
   resolved "https://registry.yarnpkg.com/sequencify/-/sequencify-0.0.7.tgz#90cff19d02e07027fd767f5ead3e7b95d1e7380c"