Documentation cleanup: Fresh links, improved formatting, build.sbt examp...

[jbnunn]

Cleaned up some formatting issues, added a fresh link to SBT (now on Github vs Google Code), added an example to show how to use build.sbt to pull in resolver and dependencies.

[schleichardt]

Since people asks on Stackoverflow (http://stackoverflow.com/questions/19532774/cassie-dependency-with-cassandra-2-0-1-and-scala-2-10-2/19534981) how to use it with SBT, it would be a good idea to update the documentation on README.md.

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