Added context specs

src/kemal/context.cr

@@ -1,15 +1,13 @@
 class Kemal::Context
   getter request
   getter params
+  getter content_type
 
   def initialize(@request, @params)
+    @content_type = "text/plain"
   end
 
-  def response
-    @response ||= Response.new
-  end
-
-  def response?
-    @response
+  def set_content_type(content_type)
+    @content_type = content_type
   end
 end

src/kemal/handler.cr

@@ -26,7 +26,7 @@ class Kemal::Handler < HTTP::Handler
         context = Context.new(request, params.not_nil!)
         begin
           body = route.handler.call(context).to_s
-          content_type = context.response?.try(&.content_type) || "text/plain"
+          content_type = context.content_type
           return HTTP::Response.ok(content_type, body)
         rescue ex
           return HTTP::Response.error("text/plain", ex.to_s)