CLI Version Resolver should take into account currently installed versions

[acburdine]

Currently the CLI version resolver (lib/utils/version.js) takes an optionally supplied version and returns a Promise that either rejects (if the version is less than 1.0.0-alpha.1 or does not exist) or resolves with the latest version (if no version is initially supplied) or the version that was initially supplied (if it's valid). It does this by parsing the output of npm view (which can output as JSON).

This should be improved to check with the currently installed versions as well as the available versions on NPM. Doing so will allow better resolution when a ghost update successfully downloads the ghost version but does not update the symlink or the activeVersion value in the config. However, if a force option is passed (see #46), then it will ignore the currently installed versions.