Split configuration into low and high traffic files

Also, we're now handling config ourselves instead of using
electron-config and config dependencies.

app/base_config.js

@@ -0,0 +1,58 @@
+const fs = require('fs');
+
+const _ = require('lodash');
+
+const ENCODING = 'utf8';
+
+module.exports = {
+  start,
+};
+
+function start(name, targetPath) {
+  let cachedValue = null;
+
+  try {
+    const text = fs.readFileSync(targetPath, ENCODING);
+    cachedValue = JSON.parse(text);
+    console.log(`config/get: Successfully read ${name} config file`);
+
+    if (!cachedValue) {
+      console.log(
+        `config/get: ${name} config value was falsy, cache is now empty object`
+      );
+      cachedValue = Object.create(null);
+    }
+  } catch (error) {
+    if (error.code !== 'ENOENT') {
+      throw error;
+    }
+
+    console.log(
+      `config/get: Did not find ${name} config file, cache is now empty object`
+    );
+    cachedValue = Object.create(null);
+  }
+
+  function get(keyPath) {
+    return _.get(cachedValue, keyPath);
+  }
+
+  function set(keyPath, value) {
+    _.set(cachedValue, keyPath, value);
+    console.log(`config/set: Saving ${name} config to disk`);
+    const text = JSON.stringify(cachedValue, null, '  ');
+    fs.writeFileSync(targetPath, text, ENCODING);
+  }
+
+  function remove() {
+    console.log(`config/remove: Deleting ${name} config from disk`);
+    fs.unlinkSync(targetPath);
+    cachedValue = Object.create(null);
+  }
+
+  return {
+    set,
+    get,
+    remove,
+  };
+}