Includes a merge of radiod and redirectord, updates to more modern Go
idioms, adoption of the higher level etcd concurrency primitives, and
a lot of other minor implementation changes.

The refactor is still incomplete: the daemons won't compile and the
code to start the RPC servers is missing.

This provides some discovery capabilities to radiod and redirectord, so
that in most cases fewer command-line options are required for operation.

This will limit useless reloads (and related killSources), for instance
when transcoding parameters change. Also, improve the icecast
config generation test.

Master election code should be more robust now, this commit eliminates
the discrepancy between role and master info (previously it was possible
for these two to be non synchronized).

This commit also includes an in-memory etcd mock, which implements
enough of the etcd interface to test the masterelection code.

Introduce node names, allowing a node to have multiple IP addresses.
Also, make the front-end code IPv6-aware and support AAAA records.