revert embedded templates to use prompt/response

This reverts commit 19753c18c0.

for compat. messages will be added at a later date

template/alpaca.gotmpl

@@ -1,15 +1,3 @@
-{{- if .Messages }}
-{{- if .System }}{{ .System }}
-
-{{ end }}
-{{- range .Messages }}
-{{- if eq .Role "user" }}### Instruction:
-{{- else if eq .Role "assistant" }}### Response:
-{{- end }}
-{{ .Content }}
-
-{{ end }}### Response:
-{{ else -}}
 {{ if .System }}{{ .System }}
 
 {{ end }}{{ if .Prompt }}### Instruction:
@@ -18,4 +6,3 @@
 {{ end }}### Response:
 {{ .Response }}
 
-{{ end -}}