java: do not .gitignore web contents under build

We are including a built version of the application under the
java-spring build directory, so we need to include that content in the
git repository by allowing git to manage the path:

build/resources/main/public
*: deploy built app to java server

So that users who do not wish to develop the browser app may still use
it, deploy a built version of the application with each build from
the browser.

Create a rewriter class in Java to support HTML5 "push state" routing.
(This turned out to be just as easy as making it support "index.html"
as the default file, and causes the URLs not to be switched up between
Node and Java renderings.)
browser build -> java server
browser: correctly launch gulp from gulp

When launching gulp tasks from within gulp, bind to the gulp instance
to avoid "isRunning" errors and breakdown of watch functionality from
improper use of Orchestrator.

Clean up error messages written to the console during build.