Build metadata should not be used when determining precedence

[smumriak]

Bullet point 10 in SemVer specification states

Build metadata MUST be ignored when determining version precedence. Thus two versions that differ only in the build metadata, have the same precedence. Examples: 1.0.0-alpha+001, 1.0.0+20130313144700, 1.0.0-beta+exp.sha.5114f85, 1.0.0+21AF26D3----117B344092BD.

[finestructure]

Thanks for the bug report, @smumriak. This is being addressed here: #11

[daveverwer]

Looks like this didn't get closed. Cleaning up now!