Allow to specify baseurl as argument

sitegin/config.js

@@ -19,6 +19,7 @@ var options = cli.parse({
  themedir: [null, 'Allows to specify arbitrary content directory.', 'string', 'theme'],
  builddir: [null, 'Allows to specify arbitrary content directory.', 'string', null],
  staticdir: [null, 'Allows to specify arbitrary directory for static files.', 'string', 'static'],
+ baseurl: [null, 'BaseURL without trailing /', 'string', ''],
  debugarticle: [null, 'Article for which extra information should be printed out. Full file path '+
  'relative to contentdir (Ex. articles/2010/hello-word.md)','string', null]
 });