Revert "Don't exclude build folder"

This reverts commit 228bda7c13a2704de120f33650820338d16420e9.
Revert "Move API to proper package"

This reverts commit 9c4b20a3b6621b3d036a4b49c217aa4c6e82605c.
Revert "Strip out unnecessary DashClock stuff and move key items to Multiplexer"

This reverts commit 30bdcb15131921b26224a7279454080fc2384112.
Some initial changes:

* Basic initial multiplexer api (incomplete)
* Revert changes 228bda7c13a2704de120f33650820338d16420e9, 9c4b20a3b6621b3d036a4b49c217aa4c6e82605c and 30bdcb15131921b26224a7279454080fc2384112
* Upgrade to gradle and support versions

Signed-off-by: Jorge Ruesga <jorge@ruesga.com>