fix(GUI): handle spaces in installation path when elevating on Windows (#1411)

Etcher will get stuck at "Starting..." when executing the application on
a directory that contains spaces, like "C:\Program Files (x86)".

The problem is that the command is not quoted correctly when passed to
`cmd.exe /c`. This commit addresses the following specific problems:

- Quote the whole argument to `cmd.exe /c`
- Quote each individual argument after `call`

Change-Type: patch
Changelog-Entry: Fix application stuck at "Starting..." on Windows.
See: https://github.com/resin-io/etcher/pull/1376
Signed-off-by: Juan Cruz Viotti <jviotti@openmailbox.org>

lib/shared/permissions.js

@@ -118,6 +118,21 @@ exports.getEnvironmentCommandPrefix = (environment) => {
   return _.concat([ 'env' ], argv);
 };
 
+/**
+ * @summary Quote a string
+ * @function
+ * @private
+ *
+ * @param {String} string - input string
+ * @returns {String} quoted string
+ *
+ * @example
+ * const result = quote('foo');
+ */
+const quoteString = (string) => {
+  return `"${string}"`;
+};
+
 /**
  * @summary Elevate a command
  * @function
@@ -143,14 +158,22 @@ exports.getEnvironmentCommandPrefix = (environment) => {
  * });
  */
 exports.elevateCommand = (command, options) => {
-  const prefixedCommand = _.concat(exports.getEnvironmentCommandPrefix(options.environment), command);
+  const isWindows = os.platform() === 'win32';
 
-  if (os.platform() === 'win32') {
+  const prefixedCommand = _.concat(
+    exports.getEnvironmentCommandPrefix(options.environment),
+    _.map(command, (string) => {
+      return isWindows ? quoteString(string) : string;
+    })
+  );
+
+  if (isWindows) {
     const elevator = Bluebird.promisifyAll(nativeModule.load('elevator'));
-    return elevator.elevateAsync(_.concat([
+    return elevator.elevateAsync([
       'cmd.exe',
-      '/c'
-    ], prefixedCommand)).then((results) => {
+      '/c',
+      quoteString(_.join(prefixedCommand, ' '))
+    ]).then((results) => {
       return {
         cancelled: results.cancelled
       };