Add breaking change documents for each service

[cormacpayne]

Description

Fix for issue #3028

• Added documentation folder for each service
  • upcoming-breaking-changes.md
    -current-breaking-changes.md
• Added script that will maintain breaking change documents during release and move the contents of each current-breaking-changes.md to the master file that will serve as the overall migration guide
• Updated contributing guide to include this information

---

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[markcowl]

Looks good, a couple of comments.

[markcowl]

For a description of breaking changes in powershell, see...

[markcowl]

Can we use Test-ModuleManifest

[markcowl]

@cormacpayne there are conflicts, please update

[markcowl]

You can use #Requires here: https://technet.microsoft.com/en-us/library/hh847765.aspx

[markcowl]

on demand run here: http://azuresdkci.cloudapp.net/view/1-AzurePowerShell/job/powershell-demand/1261/

LGTM once the ci build passes.