restructuring for easier maintenance

- creating src packages when things can't be installed via
  actual system package
- neovim srcpkg is being worked on now

tasks/pkgs/Darwin/terraform.yml

@@ -0,0 +1,4 @@
+---
+- name: append terraform to brewpkgs
+  set_fact:
+    brewpkgs: "{{ brewpkgs + [ 'terraform' ]}}"