client-side mru signatures -- step 2/5

[jpeletier]

As agreed during Tuesday's roundtable review, I am fragmenting PR #704 in incremental steps to make it easier to review. The steps are these:

• Step 1 : (PR client-side mru signatures -- step 1/5 #732) Minimum set of changes for client-side MRU signatures to work + system-time based MRUs. This was the status roughly 8 days ago.
• Step 2: (PR client-side mru signatures -- step 2/5 #733) Documentation, refactors and new, more concrete unit tests for the new structures
• Step 3: (PR client-side mru signatures -- step 3/5 #734) Refactor LookupParams so that the different combinations are documented. Moved LookupParams to its own file. Reorder code and create separate files for a few structures
• Step 4 (PR client-side mru signatures -- step 4/5 #748): Final refactors. Refactor serialization for extensibility. Refactor Timestamp to a "Timestamp" struct rather than a lone uint64. More comments throughout.
• Step 5: (PR Client-side MRU signing -- step 5/5 #704) Rewrite CLI and simplify client and internal object structure according to comments to decouple resource creation from updating.

[jpeletier]

Note:

In this step I made the mistake of renaming the resourceUpdate structure to resourceData. This will be undone in the next step. Sorry for the confusion.

[jpeletier]

To review this step, use this link: 8dd0bef, which will show the correct diff.

[jpeletier]

Sorry for this change. It was a mistake. In the next step it will be renamed back.

[jpeletier]

Moved to timestampprovider.go

[jpeletier]

parseUpdate now verifies signatures and ownership, otherwise fails.

[jpeletier]

Moved to updaterequest.go and renamed as resourceUpdateChunkDigest

[nolash]

See comments here:

8dd0bef