implement conflict resolution techniques

currently, the collector only:

• selects nearest "suggested" version in a valid range
• latest version from the valid ranges if none suggested
• fails if ranges are over-constrained

This needs to be configurable:

• select newest, even if there is a nearer suggestion
• select oldest, even if there is a nearer suggestion
• fail if all suggestions don't equate or a range results instead of a single version
• ignore over constrained ranges and fallback to some other algorithm
• select snapshots even if they weren't explicitly specified