clamd: added optional results storage
clamd: removed results conditionals
clamd doc fixes: connect_timout -> connect_timeout

only_with_attachment -> only_with_attachments
clamd config parsing improvements and tests

* consolidated config fetching into refresh_config()
* declared config opts randomize_host_order && only_with_attachments boolean
* added compat shim for only_with_attachment if only_with_attachment_s_ not defined
* simplified timeout calculations