Proxy support

[srour]

Server-side requests for google places data will sometimes come through a hosted cloud provider where outbound TCP requests are sent through different IP ranges. Since Google has IP white listing there is a need to have a static address for these requests. Using a proxy is the typical solution to this.

I've added support for specifying a proxy parameter which simply calls the node request library (and I've implictly added a dependency on the request library).