This way analytics related settings and parameters (currently
analyticsdisabled, analyticsmessage and analyticsuuid) are all kept in
the same place.
Note that in this commit we offer a path of migration: if
~/.homebrew_analytics_user_uuid already exists, read the UUID from it,
write to homebrew.analyticsuuid, and remove it.
See more detailed discussions in #145.
Closes#162.
Signed-off-by: Martin Afanasjew <martin@afanasjew.de>