desktopcouch can start multiple times leading to several running couchdbs

ubuntuone-preferences and ubuntuone-login both wait for CredentialsFound signal (in Lucid).
Both processes will interact with couchdb upon receiving of the signal, the first one will read replication exclusion, the latter will put a pairing record to the db.

It turns out that they are running so head-to-head that they initialize 2 desktopcouches. Desktopcouch checks the pid and if it is not there it will start the couchdb, however, since there are 2 simultaneous calls both processes start their own couchdb. Eventually only one pid will be written to the file, and only one couchdb will be contacted (because of dbus response being returned only by one desktopcouch instance)

This bug prevents CouchDB pairing with Ubuntu One from working consistently, which prevents users from syncing contacts and bookmarks in Lucid with CouchDB from backports installed.

TEST CASE:
1. Ensure that no couchdb and desktopcouch-service processes are running:
1.1 /usr/lib/desktopcouch/desktopcouch-stop
1.2 killall desktopcouch-service
1.3 killall beam
1.4 killall beam.smp
2. Ensure that ubuntuone-syncdaemon is running (we need ubuntuone-login to be running to test for double start)
3. Open ubuntuone-preferences from terminal
4. Run sudo netstat -lntp | grep beam, there should be only one process with beam / beam.smp
5. Verify that there is only one "Apache CouchDB has started on http://127.0.0.1:$port" line in ~/.cache/desktop-couch/desktop-couchdb.log.1