Fix intermittent TestFiltering test

This fixes a race condition where the watchSet has received the
discoverd update but the filtered set hasn't, leading to set.Services()
only returning one service and the test failing.

Signed-off-by: Lewis Marshall <lewis@lmars.net>
Merge pull request #31 from flynn/fix-intermittent-filtering-test

Fix intermittent TestFiltering test
Reconnect to discoverd when the connection drops

Signed-off-by: Lewis Marshall <lewis@lmars.net>