Update Tutorials

[albsch]

Update Mariano's tutorials in the readme for riak_core_lite.

[rotaki]

According to the tutorial, implementing handle_command in vnodes will be useful for coverage calls such as list_keys(Bucket).
However, to do so, riak_core_coverage_fsm is required, which is still not migrated to riak-core-lite. Are there any plans for this? (such as coverting riak_core_coverage_fsm to gen_statem)

[albsch]

We decided to put things outside of riak_core_lite to its own package riak_core_util. It's up to decide whether we include the coverage fsm into riak_core_lite or not (after porting it to gen_statem).
What's your opinion on this @marianoguerra , also about the coverage_fsm mechanism in general?

[albsch]

We talked about it and decided to add it to utils for now. See this issue.