just to be different, the EDN format
Update Platforms-and-APIs.md
a DateTime spec to keep in mind
Flesh out the Key-Value DB section and add an overview of DBs.

I hope that, in this interdisciplinary project, overviews like this will
let future team members orient themselves.
It seems that the sheer number of available database systems overwhelms
any one person's ability to remember and understand all the tradeoffs.
Even Couchbase only compares themselves to CouchDB:
http://www.couchbase.com/couchbase-vs-couchdb

(plus fix some typos and such that editing with github-markdown hid from me)
Merge branch 'master' into databased

Conflicts:
	wiki/Platforms-and-APIs.md
CassandraDB.
A couple more lines and hearsay that "Mongo loses your data".