Added Running section in README and RootChain migration file

[PaulRBerg]

Full list of changes:

• Added 2_deploy_rootchain.js file, as the first migration file wasn't actually deploying the RootChain contract and it wasn't available in truffle console
• Added a Running section which explains the rationale for the point above
• Rewritten Migrations's contructor to get rid of the warning, as per Solidity ^0.4.22
• Fixed some minor spelling errors in docs/rootchainFunctions.md

[coveralls]

Pull Request Test Coverage Report for Build 343

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 89.568%

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Totals
Change from base Build 340:	0.0%
Covered Lines:	180
Relevant Lines:	194

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💛 - Coveralls