Shallow support for 1.8 level bytecode in our ASM fork.

  - Allows us to emit and read classfiles with that leve
  - Allows us to read them with ClassFileReader, so long as they don't
     use default methods. This is handy for using ASMifier to show
     the ASM code needed to create a classfile compiled with Java 8.
More cleanup for invokedynamic lambas

  - disable if the method contains an value class, LambdaMetaFactory's
    box/unbox semantics can't deal with that. (TODO are there other differences
    for primitives?)
  - Rename the attachment, and only attach if we're going to use invokedynamic
  - ... which we no only do under the new -target:jvm-1.8