Add version checking logic

[dtrenz]

The library should be able to look at various forms of version strings or version codes and deduce which version is higher / lower. This will involve major and minor numbers, ex "1.2.1 vs 1.3.0" and "1.5 vs 2.1" as well as a version code that may be only an integer. The consumer should be able to configure what the library is evaluating, the version name or the version code.

see: btkelly/gandalf#5

[dtrenz]

Done. Using version string. Not configurable in this version.