v0.8.1

1. add postgres 9.4 jsonb support
2. add more json operators/functions

Note: to keep compatible, jsonb support is not on by default.

You can enable it with config like this:

trait MyPostgresDriver extends ExPostgresDriver
                          ...
                          with PgJsonSupport
                          with PgSearchSupport {
  override val pgjson = "jsonb"
  ...