WIP: untested, pass-thru items with type

When piping data to our storage backend, allow any "entry" item with a
"type" field.  If it does not have a type field, validate per usual
using sgvdata.
Merge branch 'dev' into wip/rest/mbg
require date instead of sgv
Merge pull request #189 from nightscout/wip/rest/mbg

Allow non-SGV entries to be posted to the rest API