Add convention for ABI

[tpmccallum]

We need a convention in order for the search engine to autonomously harvest many different ABI versions of the same DApp.

The python/config.ini of this search engine must adhere to the following convention.
dappname_version
Here is a real config example.

[abis]
fairplay_v1 = https://raw.githubusercontent.com/CyberMiles/smart_contracts/master/FairPlay/v1/dapp/FairPlay.abi

As you can see from the above configuration example, the key conforms to dappname_version i.e. fairplay_v1.

The harvester/indexer of this search engine will store all contracts in the "fairplay" index. Each record in the indices will have a version attribute stored within.