Support Expanded Semantic Version Syntax

[willhlaw]

Great effort here. I see that you have / are planning some versioning capabilities. Perhaps, grapnel should extend the version range concept to accommodate semantic versioning based on semver. Spec for semver is at http://semver.org/

NPM is one of the latest, well written, and heavily used implementations of semver (So is Bower). Many developers are not only beginning to follow semver after the first 1.0 release (anything is game during 0.x development) of their project, but also are adhering to the paradigm of loosely pinning their dependencies via ~ and ^ notations. See https://www.npmjs.org/doc/misc/semver.html

Here's an early 2014 discussion about how [well] developers are doing semver in node.js/nom on reddit, http://www.reddit.com/r/node/comments/1wo7n4/people_misunderstand_and_and_semver_in_nodejsnpm/