Allow locking to a specific major or minor version

[njbennett]

Currently there's no way to avoid bumping a major version, while still pulling in new minor versions automatically.

This is periodically a problem for the CF Release Integration team. All versions of all releases in cf-deployment are bumped automatically, but sometimes a team requests that we not pull in a new major version until they've done some post-release testing. We may also discover a problem with the latest version and want to pin back to an earlier version.

Right now we have to pause the resource version itself. This is fragile (we might forget why we did that) and often overly broad (there might be minor versions we could pull in.)

Our initial thought is that we'd like to be able to provide a version regex and only pull in new versions that match, similar to how the Github resource allows one to use a tag_filter. We have a mostly-complete PR that takes this approach, but we're not wedded to that as the implementation.