[CSL-789] Explicitly maintain Appveyor caches for important branches (#49)
[CSL-789] Explicitly maintain Appveyor caches for important branches (#49)

* [CSL-789] Explicitly maintain Appveyor caches for important branches

* [CSL-789] Replace '/' in Appveyor branch cache dirs

* [CSL-789] Diagnostic messages for Appveyor cache

* [CSL-789] Use Appveyor init section to set cache env vars

input-output-hk/pos-haskell-prototype,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/cardano-sl,input-output-hk/pos-haskell-prototype,input-output-hk/cardano-sl,input-output-hk/cardano-sl