Use <Operations>/JobDescription for the job parameter default and check
values
Allow to override pilot DN/Group in the SiteDirector options
Use operations helper to get job parameter default values
If SiteDirector is for a given group, take the SubmitPools from the
group
If SubmitPools defined in the Group CS options, take it from there,
otherwise from the VO settings.
Reset signal.alarm(0) if file to download not found
Merge pull request #1258 from atsareg/fix

[v6r7] Several fixes