STORM-668:Generate storm-ui.war and could be deployed on TomCat

[caofangkun]

➜  storm-core git:(storm-668) mvn clean &&  mvn install -Dmaven.test.skip=true -Dwar
➜  storm-core git:(storm-668) cp target/storm-ui.war $TOMCAT_HOME/webapps/

[d2r]

@caofangkun This is an interesting idea. With the provided code, we can run storm ui to verify things are working as expected. Testing this functionality is going to be more difficult, as it would require spinning up a tomcat server to verify everything still works. Do you have advice on how we might be able to do that?

[caofangkun]

@d2r
Thank you for your attention of this PR.
In my opinion ,
1, "storm ui" is more like a RESTful APIs server than a UI server.
2, We can use jetty embedded server (as the provided code use) for testing;
but on production environment, use Apache Tomcat or other WebSever Container may be a better choice.
I have implement these as a external project storm-ui .

[d2r]

@caofangkun OK, let's add a short section to DEVELOPER.md or another doc with:

• Build and tomcat integration instructions from your earlier comment
• Disclaimer saying that it is not tested and so it may not work correctly

It will not be built by default, but only if we include -Dwar, so I think it should be OK.

[revans2]

@caofangkun it looks like there were only a few minor nits before this could go in. Do you still want this to go in? if so could you please upmerge and update the documentation as @d2r has requested?

[caofangkun]

@revans2 This branch is outdated too much, I pushed a new request as #992 .