feat: added basic unit testing. Also separated migrations to separate sql and go migrations. This makes it easier to unit test where we just need sql migrations.

db/sql/20191210181732_create_workflow_template_versions.sql

@@ -0,0 +1,15 @@
+-- +goose Up
+CREATE TABLE workflow_template_versions
+(
+    id                      serial PRIMARY KEY,
+    workflow_template_id    integer NOT NULL REFERENCES workflow_templates ON DELETE CASCADE,
+    version                 integer NOT NULL,
+    manifest                text NOT NULL,
+
+    -- auditing info
+    created_at              timestamp NOT NULL DEFAULT (NOW() at time zone 'utc'),
+    modified_at             timestamp
+);
+
+-- +goose Down
+DROP TABLE workflow_template_versions;