UI / Config : new and updated Subscription should be able to get more than 30 commits

[SRombauts]

When Adding a new Subscription the tool should be configurable to grab more than 30 commits (in CommitMonitor I ask for the maximum, which is 1000)

When updating after a few day offline, the tool should be able to grab all the commit (currently losing the commits if there was more than 30 since last time)