Feature/12 ibc dispatcher

[taitruong]

The objective of this (not yet finished) contract is the following:

• a source contract on chain A wants to execute
• a target contract on chain B, where in return
• source contract gets a response back from target contract.

This can already be done by using IBC - hence this requires a lot of boiler plate code. Basically all IBC calls looks the same.

IBC dispatcher to the rescue:

• a source chain can pass target message along with target contract address and IBC channel (telling on which chain it is) and
• pass this message to the dispatcher, where
• dispatcher pass it to target contract on the other channel, where in return
• source target gets a response back from the dispatcher

[taitruong]

@javierjmc, @Japarjam