Implemented command line config overrides

You can set the file to read as the config file via the command line, like
this, assuming the program supports it:

  prog -config=file.cfg

You can also override indevidual key-value pairs in the config system
using this syntax:

  prog -Ckey=value

Both commands can be used together, and you can override multiple
key-value pairs at once. To use this feature of the ConfigUtility, it must
receive argc and argv as parameters to the Load() method.

common/utilities/config_utility.hpp

@@ -29,7 +29,7 @@
 
 class ConfigUtility : public Singleton<ConfigUtility> {
 public:
-	void Load(std::string fname);
+	void Load(std::string fname, int argc = 0, char* argv[] = nullptr);
 
 	//convert to a type
 	std::string& String(std::string);