couch:start/0 masks failures during startup

couch:start/0 ignores the result of application:start/1, masking any errors that happen during startup. e.g. I didn't have Erlang's os_mon modules (from Ubuntu's erlang-os-mon package) installed which caused current couchdb trunk to silently fail to start. The following trivial patch makes it fail immediately:

diff --git a/src/couchdb/couch.erl b/src/couchdb/couch.erl
index 956e948..365416e 100644
— a/src/couchdb/couch.erl
+++ b/src/couchdb/couch.erl
@@ -15,7 +15,8 @@
-compile(export_all).

start() ->

• application:start(couch).
  + ok = application:start(couch),
  + ok.

stop() ->
application:stop(couch).