Set the type of Bookmark.Port to int

We know that a port is a number. Lets enforce that
rule at type level by setting it so.

This commit also adjusts test funcs and helper data
to fit Port's new int type.

pkg/bookmarks/bookmarks.go

@@ -15,7 +15,7 @@ import (
 type Bookmark struct {
 	Url      string         `json:"url"`      // Postgres connection URL
 	Host     string         `json:"host"`     // Server hostname
-	Port     string         `json:"port"`     // Server port
+	Port     int            `json:"port"`     // Server port
 	User     string         `json:"user"`     // Database user
 	Password string         `json:"password"` // User password
 	Database string         `json:"database"` // Database name