WIP: Introduce a struct for managing command line arguments without cargo dependencies

[jtimon]

This should make it much easier to add, remove or document parameters. There's probably hundreds of better argument parsers, but I wasn't able to chose, passing integration tetes shouldn't take much and I also wanted to be able to set certain parameters by chain and just ignore them if they're set but the chain is not selected.

I'm still learning rust, be harsh to the code, not to me, please.

I think this could help with https://github.com/TheBlueMatt/rust-lightning-bitcoinrpc/issues/7

[jtimon]

Rebased. @TheBlueMatt , this should now pass or fail travis tests as soon as you enable them.