Move intall `happy` command into `script`
Move intall `happy` command into `script`

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