Gather the parachain constants for different runtimes

[clearloop]

Issue summary

Gather the parachain constants in one crate, for example:

pub struct ParaChain {
    id: usize, 
    name: Vec<u8>,
    weights: RuntimeCallWeights,
}

Maybe we can place it in primitives/parachain or runtime/common, this is necessary for our cross-chain transactions, and we can use these to make the error info more detailed for cross-chain transactions.

These types should be done by polkadot team, not sure if there already has some repo or crate provide this.

Other information and links

• configure xcm call weights as constants for different runtimes #159
• extract common config types to a common crate #156
• parachains of kusama

[mattsse]

This makes sense, however, this would require that all come with RuntimeCallWeights and since support for staking/proxy will be very specific we can keep this separate.