Add support for multiple metadata signatures

Add the ability for the PowerShell cmdlets to pair with either of two
different metadata signatures. This will allow us to upgrade the
metadata signature without breaking PowerShell. Also updated the latest
signature to that of the latest management service.
Support arbitrary number of metadata signatures
Fix static metadata issue

- Actually use the computed metadata hash in the update script
- Fix a typo
- Shorten a verbose loop to one linq.Any() call.
Merge pull request #1 from bcham/dev

Add support for multiple metadata signatures
Merge remote-tracking branch 'remotes/upstream/dev' into dev
Merge pull request #1156 from WindowsAzure-SqlDb/dev

Add support for multiple metadata signatures