Allows users to send post requests to next_network and next_address

[rmhasan]

Should be merged alongside dropbox/nsot#266. This allows users to send post requests to the next_network and next_address actions through the nsot networks add command. It allows users to users to send the reserve parameter to the next_network and next_address actions also.

[jathanism]

Now that we're about to release dropbox/nsot#266 let's revisit this and get it pretty!

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