Fixed map votes not giving an extension option

Sometimes map votes would not offer an option to extend the map even
though it was enabled in the config.
Made forcing map extension a config option

Set "AlwaysExtend" to true if you want a map extension to always be
included in the vote list. Otherwise it will be a random option like the
rest.
Merge pull request #25 from Person8880/develop

Added option to force the current map to be a vote option.