[CSE-68] Add command to install `happy`
[CSE-68] Add command to install `happy`

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