HTTP Triggers hookup (#1086)

* Initial suypport for invoking tiggers

* dupe method

* tighten server constraints

* runner tests not working yet

* basic route tests passing

* post rebase fixes

* add hybrid support for trigger invoke and tests

* consoloidate all hybrid evil into one place

* cleanup and make triggers unique by source

* fix oops with Agent

* linting

* review fixes

api/server/trigger_get.go

@@ -1,11 +1,10 @@
 package server
 
 import (
-	"net/http"
-
 	"fmt"
 	"github.com/fnproject/fn/api"
 	"github.com/gin-gonic/gin"
+	"net/http"
 )
 
 func (s *Server) handleTriggerGet(c *gin.Context) {