[enh] add BMA watcher + reorganize code

package.json

@@ -7,6 +7,7 @@
   "license": "MIT",
   "dependencies": {
     "@types/minimist": "^1.2.0",
+    "axios": "^0.19.0",
     "duniter": "^1.8.0",
     "js-yaml": "^3.12.1",
     "minimist": "^1.2.0",
@@ -14,6 +15,7 @@
     "typescript": "^3.4.3"
   },
   "devDependencies": {
+    "@types/axios": "^0.14.0",
     "@types/js-yaml": "^3.12.0",
     "@types/node": "~8.9.4",
     "@types/nodemailer": "^6.1.1"