Revert to head of fork.
This reverts commit a7083174bbc54af4a158c0b34c7762b37afd1e0c.
Revert "Disable code analysis on PushSharp.Core."

This reverts commit e047e3a844dd8b814aed74e97f9857a45c6fb857.
Revert "Create protected method to raise channel exception."

This reverts commit b43da536e1fb5e7c471592f6151cd1f9ccf9bea1.
Revert "Restore OnChannleException"

This reverts commit 638d33af8cdf8c1e3136b5eff44224409bcfb454.
Revert "Remove code that is generating code warnings."

This reverts commit 888d71aed0c54d35d1ba98e2037ed4998acc7086.
Revert "Kill NuGet restore. Add stage configuration to core, android, apple."

This reverts commit e3dd93118412312f7f142403e9fc3a53ca2763df.
Always include sound payload in Content-available. But don't overwrite
existing sound.