Better/faster exporting

* add --build and --build-dir options to sapper export (#325)

* tweak export logging, update port-authority to prevent timeout bug

* better logging of export progress

* handle case where linked resource is already fetched

* default to .sapper/dev instead of .sapper

* handle query params and redirects

* dont write server_info.json either - second half of #318

* update changelog

* update lockfile

* try to track down ci test failures

* err wut

* curiouser and curiouser

* ok, seems to work now

package.json

@@ -28,7 +28,7 @@
     "html-minifier": "^3.5.16",
     "mkdirp": "^0.5.1",
     "node-fetch": "^2.1.1",
-    "port-authority": "^1.0.2",
+    "port-authority": "^1.0.5",
     "pretty-bytes": "^5.0.0",
     "pretty-ms": "^3.1.0",
     "require-relative": "^0.8.7",