Adds support for timestamps and enums
Takes out bad changes to StringValueEncoder
Merge remote-tracking branch 'origin/timestamp-enum-support' into additional_oids

Conflicts:
	src/main/scala/com/twitter/finagle/postgres/protocol/Values.scala
make this support hstore (and enums) properly
Merge branch 'additional_oids' into thefactory

Conflicts:
	src/main/scala/com/twitter/finagle/postgres/protocol/Values.scala