Curl should be silent, unless there is an error to report

It's pretty annoying to get curl(1) output in the middle of an agent run like such:

````
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli.jar]/Package[curl]/ensure: ensure changed 'purged' to 'present'
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli-adapters.jar]/Exec[download digest of archive tomcat-juli-adapters.jar]/returns: executed successfully
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli.jar]/Exec[download digest of archive tomcat-juli.jar]/returns: executed successfully
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli.jar]/Exec[download archive tomcat-juli.jar and check sum]/returns:   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli.jar]/Exec[download archive tomcat-juli.jar and check sum]/returns:                                  Dload  Upload   Total   Spent    Left  Speed
100 63439  100 63439    0     0  10670      0  0:00:05  0:00:05 --:--:-- 81751xec[download archive tomcat-juli.jar and check sum]/returns: 
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli.jar]/Exec[download archive tomcat-juli.jar and check sum]: Triggered 'refresh' from 1 events
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli.jar]/Exec[rm-on-error-tomcat-juli.jar]: Triggered 'refresh' from 1 events
Notice: /Stage[main]/Tomcat::Juli::Debian/File[/bin/tomcat-juli.jar]/ensure: created
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli-adapters.jar]/Exec[download archive tomcat-juli-adapters.jar and check sum]/returns:   % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
Notice: /Stage[main]/Tomcat::Juli::Debian/Archive::Download[tomcat-juli-adapters.jar]/Exec[download archive tomcat-juli-adapters.jar and check sum]/returns:                                  Dload  Upload   Total   Spent    Left  Speed
100 22996  100 22996    0     0   4095      0  0:00:05  0:00:05 --:--:-- 50429rs.jar]/Exec[download archive tomcat-juli-adapters.jar and check sum]/returns: 
````

So perhaps curl should not print anything (`-s`) unless there's an error to report (`-S`)?