Datastore refactor and added postgres tests (#259)

* fix apps & routes creation/update

* refactor datastore and added postgres tests

* added test-datastore and fixed circleci test

api/server/server.go

@@ -3,6 +3,7 @@ package server
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"io/ioutil"
 	"net/http"
 	"path"
@@ -185,6 +186,8 @@ func (s *Server) bindHandlers() {
 	engine.NoRoute(handleSpecial)
 }
 
+var ErrInternalServerError = errors.New("Something unexpected happened on the server")
+
 func simpleError(err error) *models.Error {
 	return &models.Error{&models.ErrorBody{Message: err.Error()}}
 }