CLI: Support for semver matching

This PR closes #82
This fixes a latent bug that comes from the fact that before the use of semver the *target* version **was** the *installed* version. With semver the *target* version can be a range.

This actually ok with widget dependencies (although I don’t do it) because **gitTio is the only responsible of widgets** but with modules, it would break the titanium toolchain, which expect a **matching version to be put in the `version` attribute of the `<module />` element**.

Needs further review, IMHO.