Complete owned entity JSON support for all type mappings

[roji]

JSON owned entity support was added in #2759, adding JsonValueReaderWriter support for most type mappings; however, some of the more complicated mappings were left out, and therefore cannot be used inside JSON-mapped owned entities. These include:

• Geometry type mappings (box et al.)
• Hstore
• Ranges and multiranges [lower, upper] - but exclusivity
• Regconfig/regdictionary
• TsQuery/TsVector
• PostGIS
• NodaTime (done in #2945)

(do an additional pass to make sure that there aren't others missing)

Note that the actual JSON representation needs to be convertible to the relational type, as well as be parsable by the JsonValueReader.