Update NPM version in all projects.

According to Node 10.15.3 (LTS) we are currently in NPM v6.4.1. Few days
ago, NPM released the 6.9.0 (cf. https://npm.community/t/release-npm-6-9-0/5911).

Upgrading the NPM version will add a step in the environment
installation. But not doing so, display a waring during each `npm
install` command execution.

In the next steps, we will try to upgrade Node version (with the risk of
leaving a comfortable LTS version). If the upgrade does not work, we
will have to take a decision about the version we keep of Node / NPM.

Maybe the PR associated to this commit will never finished in production. 🤷‍♀️

README.md

@@ -18,7 +18,7 @@ Installation
 Vous devez au préalable avoir correctement installé les logiciels suivants :
 
 * [Git](http://git-scm.com/) (2.6.4)
-* [Node.js](http://nodejs.org/) (v10.15.3) et NPM (6.4.1)
+* [Node.js](http://nodejs.org/) (v10.15.3) et NPM (6.9.0)
 * [Ember CLI](http://ember-cli.com/) (3.7.0)
 
 ⚠️ Les versions indiquées sont celles utilisées et préconisées par l'équipe de développement. Il est possible que l'application fonctionne avec des versions différentes.

admin/package.json

@@ -22,7 +22,7 @@
     "coverage": "COVERAGE=true ember test",
     "dev": "ember serve",
     "lint": "eslint .",
-    "preinstall": "test \"$(npm --version)\" = 6.4.1",
+    "preinstall": "test \"$(npm --version)\" = 6.9.0",
     "scalingo-post-ra-creation": "echo 'nothing to do'",
     "start": "ember serve --proxy",
     "test": "ember exam",

api/package.json

@@ -91,26 +91,23 @@
     "coverage:check": "NODE_ENV=test npm run db:migrate && NODE_ENV=test nyc --silent _mocha --recursive --exit --reporter dot tests && nyc report --reporter=lcovonly --report-dir=../coverage",
     "coverage:rename": "mv ../coverage/lcov.info ../coverage/api_lcov.info",
     "coverage": "npm run coverage:check && npm run coverage:rename",
-
     "db:sqlite:delete": "rm -f db/dev.sqlite3 db/dev.sqlite3-journal db/test.sqlite3 db/test.sqlite3-journal",
     "db:sqlite:empty": "node scripts/database/empty-database",
     "db:sqlite:migrate": "knex --knexfile db/knexfile.js migrate:latest",
     "db:sqlite:prepare": "npm run db:sqlite:delete && npm run db:sqlite:migrate",
     "db:sqlite:seed": "knex --knexfile db/knexfile.js seed:run",
     "db:sqlite:reset": "npm run db:sqlite:prepare && npm run db:sqlite:seed",
-
     "db:pg:create": "node scripts/database/create-database",
     "db:pg:delete": "node scripts/database/drop-database",
     "db:pg:empty": "node scripts/database/empty-database",
     "db:pg:migrate": "knex --knexfile db/knexfile.js migrate:latest",
     "db:pg:prepare": "npm run db:pg:delete && npm run db:pg:create && npm run db:pg:migrate",
     "db:pg:seed": "knex --knexfile db/knexfile.js seed:run",
     "db:pg:reset": "npm run db:pg:prepare && npm run db:pg:seed",
-
     "dev": "nodemon bin/www",
     "lint": "eslint lib tests",
     "lint:fix": "eslint lib tests --fix",
-    "preinstall": "test \"$(npm --version)\" = 6.4.1",
+    "preinstall": "test \"$(npm --version)\" = 6.9.0",
     "scalingo-background-job": "node scripts/reload-cache-everyday.js",
     "scalingo-postbuild": "echo 'nothing to do'",
     "scalingo-post-ra-creation": "npm run db:pg:seed",