[storm] Database disconnection detection

[Gustavo Niemeyer]

Hey James!

> I've just merged support for handling database disconnections in Storm.

Thanks a lot for the feature and the nice implementation!

> There are a few caveats though:
>  1. the disconnection tests try to connect to the test database via
> TCP.  You will probably need to edit pg_hba.conf to allow this.

As we discussed, I've changed that behavior a little bit on trunk.

There are two different URIs which may be set for tests using environment
variables.  Specifically:

    STORM_POSTGRES_HOST_URI - Should be set to a URI with a hostname, such
    as "postgres://localhost/storm". This will be used for the
    disconnection test specifically.

    STORM_POSTGRES_URI - Should be set to an URI for a postgres database,
    with or without the host part.  Notice that tests run faster if this is
    set to something like "postgres:storm".

Both are optional.  The specific tests are disabled when they're not
present.  Notice that these URIs may include username/passwords as wanted.

-- 
Gustavo Niemeyer
http://niemeyer.net