Rethinking handling of WebJars and NodeJS JavaScript libs

The way this branch was handling this that V8 would load up libraries
from Node, and then an SBT task would extract the libs from WebJars
(which need to be declared, so things depending on Tortoise also get
those WebJars), and then the test webpage and SpiderMonkey and Nashorn
would use those extracted-from-WebJar files.

Now, V8 and the test webpage use the files obtained from Node, while
SpiderMonkey and Nashorn read the '.js' files out of the WebJars by
using WebJars Locator.  No more '.js' files being extracted.
Moving bootstrapping code to the right place

The old code was functioning, but the extra three dependencies on
`Workspace` shouldn't have been there.  The reason that they got put
there at all was a bit of forgetfulness on my part, I guess.  I doesn't
help that the way RequireJS handles this stuff is a bit confusing to me.
For some reason, certainly modules can't be loaded at certain times if
they weren't a part of the initial burst of module-loading.  Seems
pretty silly to me, but whatevs....