Add support for 'triton datacenter get' to node-triton.

[YangYong3]

Add support for 'triton datacenter get' to node-triton.

https://apidocs.joyent.com/cloudapi/#GetDatacenter

[YangYong3]

https://cr.joyent.us/#/c/1621/

[jclulow]

Have you seen triton datacenters? For example:

$ triton datacenters 
NAME       URL
eu-ams-1   https://eu-ams-1.api.joyentcloud.com
us-east-1  https://us-east-1.api.joyentcloud.com
us-east-2  https://us-east-2.api.joyentcloud.com
us-east-3  https://us-east-3.api.joyentcloud.com
us-sw-1    https://us-sw-1.api.joyentcloud.com
us-west-1  https://us-west-1.api.joyentcloud.com

I'm not completely clear on what new functionality triton datacenter get would provide.

[bahamat]

Considering that GetDataenter returns a 302 redirect to the CloudAPI endpoint of that datacenter, this doesn't seem to have any utility for a CLI tool, especially considering that ListServices already exists and is expressed as triton services.

That being the case, I'm going to close this issue and the accompanying PR (#269).