PG 10 issues

[erthalion]

Hello,

I tried to use pg_view on PG10, and found two issues:

• at least on my installation PG_VERSION contains just 10, so this code is causing an error about uninitialized variable version:

if val is not None and len(val) >= 2:
    version = float(val)
else:
    dbname = get_dbname_from_path(pg_dir)
    postmasters[pg_dir] = [pid, version, dbname]

• pg_xlog was renamed to pg_wal (see the corresponding message and commit)

Of course it's easy to fix them, but I'm not sure how to do it in a backward compatible way.

[LappleApple]

Hello @erthalion, would you be up for making a bug fix/PR here? Then we can review and get this fixed faster for you.

[erthalion]

From what I see #84 should be enough for the "pg_wal" part, and we can forget about an issue with PG_VERSION, since on the current PG10 beta1 everything is fine.

[alexeyklyukin]

Fixed in #84