Remove ScriptAddonReplaceScript.

Use a parameter to ScriptAddonFactoryByScript instead.
Move the AOM data update later in the install process.

When config.install() called ScriptAddonFactoryByScript(), it was creating the new ScriptAddon with the Script in its partially installed state.  Move this call to later in RemoteScript.install(), when this state has been correctly initialized.

Fixes #1778