Parameterize g.domain in DomainSR title.

The domain is not "reddit.com" on other sites. This also fixes the issue
of doing concatenation of internationalized strings which is a bad idea.
Fixes reddit/reddit#968.
Put media_domain warning on stderr to protect MR jobs.

For simple installs of reddit, g.domain == g.media_domain.  If this is
the case, the app will print a warning at startup.  However, this
warning was printed to stdout which meant that any jobs (such as the
mr_top stuff) using the output of a reddit process would get this
warning in their data streams. Bad times.
Combine and generalize the time listing precomputer scripts.

Previously, the subreddit/domain and account precomputers were separate.
This merges the two and improves their portability in the process.
Because of the increased portability, the precomputer can now be added
to the install script by default.