update Rollup, remove some superfluous deps

package.json

@@ -38,7 +38,6 @@
     "eslint": "^5.12.1",
     "eslint-plugin-import": "^2.16.0",
     "kleur": "^3.0.1",
-    "mkdirp": "^0.5.1",
     "mocha": "^5.2.0",
     "node-fetch": "^2.3.0",
     "npm-run-all": "^4.1.5",
@@ -47,7 +46,6 @@
     "pretty-bytes": "^5.1.0",
     "puppeteer": "^1.12.0",
     "require-relative": "^0.8.7",
-    "rimraf": "^2.6.3",
     "rollup": "^1.1.2",
     "rollup-plugin-commonjs": "^9.2.0",
     "rollup-plugin-json": "^3.1.0",
@@ -57,7 +55,6 @@
     "rollup-plugin-sucrase": "^2.1.0",
     "rollup-plugin-svelte": "^5.0.1",
     "sade": "^1.4.2",
-    "sander": "^0.6.0",
     "sirv": "^0.2.2",
     "sucrase": "^3.9.5",
     "svelte": "^3.0.0-alpha27",