kv-store: support quoted values

In the case of the value contains whitespaces, it has to be surrounded
with quotes (single or double).

We should exclude these characters from the final values.

Signed-off-by: Mathieu Tortuyaux <mtortuyaux@microsoft.com>

Author: tormath1

src/update_engine/simple_key_value_store.cc

@@ -27,7 +27,14 @@ map<std::string, std::string> ParseString(const string& str) {
     string::size_type pos = it->find('=');
     if (pos == string::npos)
       continue;
-    ret[it->substr(0, pos)] = it->substr(pos + 1);
+    string val = it->substr(pos + 1);
+    if ((val.length() >= 2) &&
+      ((val.front() == '\"' && val.back() == '\"') ||
+      (val.front() == '\'' && val.back() == '\''))) {
+      val = val.substr(1, val.length() - 2);
+    }
+
+    ret[it->substr(0, pos)] = val;
   }
   return ret;
 }