I recently added working directory as a mixin level config, which lets the user override the default directory with all their terraform files. #61 Sometimes people have multiple terraform modules though, and its not possible to use more than one in the same bundle. We should add working directory to the terraform mixin command so that you can do something like this:

install:
  - terraform:
       workingDir: mymodule1
  - terraform:
       workingDir: mymodule2