Update nuget
Retry to upload packages to nuget, and do not fail the build if we fail to upload. Once we fail, we will retry to upload the nuget packages manually.
Upload should occur before uploading to nuget. Failing to upload to nuget, should not failing the build, so we can see the build in the builds page.
Fix the build script
Separate the build task. We will have the following:

This is the same as the previous behaviour:
- UploadStable
- UploadUnstable

This is for creating the zip package only:

- Stable, DoRelease
- Unstable, DoRelease

This is for uploading to S3:

- Stable, Upload
- Unstable, Upload

This is for uploading to nuget:

- Stable, UploadNuget
- Unstable, UploadNuget