Add the capability to serve static resources

From the spring-xd-ui project.
Committing the UI contents
delete unused files
Re-enable CORS support

See: https://jira.springsource.org/browse/XD-730?focusedCommentId=92959&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-92959
XD-717 Avoid duplicate data on XD shell console

- Set JLineLogHandler's 'suppressDuplicateMessages' flag to false to allow
  logger to display duplicate messsages on xd shell console
Add gradle task to copy admin-ui into spring-xd-dirt META-INF/admin-ui
Updated Rest config to refer to META-INF/admin-ui
Move spring-xd-ui into spring-xd-dirt/src/main/resources/META-INF/admin-ui
- This will enable both auto-refresh on changing the ui code
  to update at the admin servlet container
- Make the admin-ui under the admin server's classpath
Removed bower dependency on the UI for now
- This is only the short term solution until we figure out
  the way to build the UI through gradle