Make history mode configurable

Author: mojodna

README.md

@@ -18,6 +18,12 @@ npm install
 CATALOG_URL=http://path/to/catalog.json npm start -- --open
 ```
 
+STAC Browser defaults to using [HTML5 History
+Mode](https://router.vuejs.org/guide/essentials/history-mode.html), which can
+cause problems on certain web hosts. To use _hash mode_, set
+`HISTORY_MODE=hash` when running or building. This will be compatible with
+S3, etc.
+
 ## Building
 
 ```bash

src/main.js

@@ -175,7 +175,7 @@ const main = async () => {
 
   const router = new VueRouter({
     base: process.env.PATH_PREFIX || "/",
-    mode: "history",
+    mode: process.env.HISTORY_MODE || "history",
     routes
   });