Fix issues 16739817 and 16709247 in voice interaction service.

Issue #16739817 VIS doesn't start for non-primary user(s)
Issue #16709247 GSA is not the default voice interaction agent

These are both fixed by getting rid of the existing code for applying
the default voice recognizer, moving it in to the voice interaction
manager service, and extending it to also set up the default voice
interaction service.

Change-Id: If8d5936c28aebfa7eff77c8d99241c3a2ffdb0a4