Update deprecations

Author: josevalim

lib/ecto/adapters/sql.ex

@@ -315,9 +315,6 @@ defmodule Ecto.Adapters.SQL do
   _Postgrex_: Check [PostgreSQL doc](https://www.postgresql.org/docs/current/sql-explain.html)
   for version compatibility.
 
-  _MyXQL_: `EXTENDED` and `PARTITIONS` opts were [deprecated](https://dev.mysql.com/doc/refman/5.7/en/explain.html)
-  and are enabled by default.
-
   Also note that:
 
     * Currently `:map`, `:yaml`, and `:text` format options are supported
@@ -635,30 +632,6 @@ defmodule Ecto.Adapters.SQL do
 
   @doc false
   def __before_compile__(driver, _env) do
-    case Application.get_env(:ecto, :json_library) do
-      nil ->
-        :ok
-
-      Jason ->
-        IO.warn """
-        Jason is the default :json_library in Ecto 3.0.
-        You no longer need to configure it explicitly,
-        please remove this line from your config files:
-
-            config :ecto, :json_library, Jason
-
-        """
-
-      value ->
-        IO.warn """
-        The :json_library configuration for the :ecto application is deprecated.
-        Please configure the :json_library in the driver instead:
-
-            config #{inspect driver}, :json_library, #{inspect value}
-
-        """
-    end
-
     quote do
       @doc """
       A convenience function for SQL-based repositories that executes the given query.

lib/ecto/migrator.ex

@@ -216,14 +216,6 @@ defmodule Ecto.Migrator do
   """
   @spec up(Ecto.Repo.t, integer, module, Keyword.t) :: :ok | :already_up
   def up(repo, version, module, opts \\ []) do
-    opts =
-      if log_sql = opts[:log_sql] do
-        IO.warn(":log_sql is deprecated, please use log_migrations_sql instead")
-        Keyword.put(opts, :log_migrations_sql, log_sql)
-      else
-        opts
-      end
-
     conditional_lock_for_migrations module, version, repo, opts, fn config, versions ->
       if version in versions do
         :already_up
@@ -286,14 +278,6 @@ defmodule Ecto.Migrator do
   """
   @spec down(Ecto.Repo.t, integer, module) :: :ok | :already_down
   def down(repo, version, module, opts \\ []) do
-    opts =
-      if log_sql = opts[:log_sql] do
-        IO.warn(":log_sql is deprecated, please use log_migrations_sql instead")
-        Keyword.put(opts, :log_migrations_sql, log_sql)
-      else
-        opts
-      end
-
     conditional_lock_for_migrations module, version, repo, opts, fn config, versions ->
       if version in versions do
         do_down(repo, config, version, module, opts)
@@ -408,14 +392,6 @@ defmodule Ecto.Migrator do
   """
   @spec run(Ecto.Repo.t, String.t | [String.t] | [{integer, module}], atom, Keyword.t) :: [integer]
   def run(repo, migration_source, direction, opts) do
-    opts =
-      if log_sql = opts[:log_sql] do
-        IO.warn(":log_sql is deprecated, please use log_migrations_sql instead")
-        Keyword.put(opts, :log_migrations_sql, log_sql)
-      else
-        opts
-      end
-
     migration_source = List.wrap(migration_source)
 
     pending =