Refactor application container

The only new functionality in this PR is the initial stubbing out of a tags service.

Otherwise, it is a bugfix, which brings samplestack java up to working with changes in patches at server and Java API level.

Use a nightly from 10/10  (today's trunk works)
The Java Client snapshot must be updated.  Try:

rm -rf ~/.gradle/caches

to force gradle to refetch ALL dependencies -- this can take a few minutes, but ensures you've got the right Java Client API.  There are less invasive ways to refresh the cache, but this is most fullproof.

Verified all tests pass on todays build, E2E still works, static application serving checked into java code also works.

Issues fixed: #212 #71