- otherwise this journey is testing not the latest copy of xjava, but
  what's at origin/master.
- add progress indicator.
- x-api can't serve binaries; must clean xjava of any build artifacts
  (e.g. .class files) before attempting to serve.

Signed-off-by: Bronwyn Perry-Huston <bronhuston@gmail.com>
Signed-off-by: Cen Ge <cge@corelogic.com>
Signed-off-by: John Ryan <jtigger@infosysengr.com>

With exercism/exercism.io@54e1df3, we can now gather exercises into a
subdirectory. By separating the language track files from the
configuration and management files, it is easier to read the project.

- move gradle config under "exercises" too as it would make a mess
  otherwise.