Make our nightly builds identical for each platform - part 1

The way we do nightly builds every night for Firefox 2.0.0.x and Firefox 3.0.x have few problems that will be good to have them fixed.

1. The build for each platform happens AFTER a determined hour BUT whenever the build slave can start it. Therefore, the build start time is different from platform to platform. This will be even more obvious when the buildID will capture minutes and seconds. This is not a big problem but it is not a correct behavior and it would be good to have the same buildID for all 3 platforms.
   
2. The build for each platform is NOT build from the same source code. You knew it or not, this has been happening for many years. This is a big problem specially when a commit to the source code happens around the time that the nightly builds are to happen and this change might be captured by one platform and not by the others. This problem affects when you want to see if a bug introduced in one of the platforms is part of the other two platforms

Things we are doing to improve this

1. Separating the generation of nightly builds from generating dependent builds
   For years, we have generated dependent and nightly builds from the same slave running the exact same code all day. We generate nightly builds after the last dependent build that gets finished after 3AM PDT. Each platform finishes at different time and each platform checks out different source code. To be more precise a nightly build is started if 1) it is passed the $build_hour and 2) twenty four hours have passed since the last nightly build. To stop the dependt builds process to generate nightly builds we need to set $OfficialBuildMachinery to zero in the tinder-config.pl
2. Use Nightly scheduler to trigger nightly builds
   Using a nightly scheduler will allow us to add more steps after an en-US nightly build like trigerring L10n repackages and/or trigger other schedulers as needed
   
3. Setting the checkout time before the build starts
   If we set up the same MOZ_CO_DATE for the 3 different platforms before the build start they will check out the same source stamp no matter when the slave will start the build
   
4. Remember the checkout time
   Saving the SourceStamp inside of the application.ini file will allow us to know which SourceStamp was used for that build even if the log for that build gets removed from the tinderbox logs

How would things look like after these changes?





















As the image shows:

1. Our nightly builds will not depend on previous dependent builds
2. The nightly builds will be triggered when we say
3. The nightly builds will check out the same source code
4. From a binary we will know which source stamp was used to generate the build