Improve dynamic errors some more
Begin 3.1.1-SNAPSHOT
Vastly improve JValue's "dynamic"

..but it's not binary compatible, so call it "dyn" and @deprecate
"dynamic".
3.1.1
Merge branch '3.1'

Conflicts:
	README.markdown
	build.sbt
	src/main/scala/com/rojoma/json/v3/ast/ast.scala
	src/main/scala/com/rojoma/json/v3/dynamic/DynamicJValue.scala