[conformal/btcec] d043ce: Add test coverage badge to README.md.

[Dave Collins]

  Branch: refs/heads/master
  Home:   https://github.com/conformal/btcec
  Commit: d043cea4909ed05d23ddbcef2721f8af403ab4ef
      
https://github.com/conformal/btcec/commit/d043cea4909ed05d23ddbcef2721f8af403ab4ef
  Author: Dave Collins <da...@conformal.com>
  Date:   2014-08-10 (Sun, 10 Aug 2014)

  Changed paths:
    M README.md

  Log Message:
  -----------
  Add test coverage badge to README.md.