Refactoring: remove nested meta data attributes from media_resource

Squashed commit of the following:

commit 8f3aaa1fe1282a9346ab108a72b86f38a4a8e7ab
Author: Thomas Schank <DrTom@schank.ch>
Date:   Mon Oct 14 09:28:33 2013 +0200

    Fix media_set_controller

commit adc6055772bad6bde91dc4bdaa21dc219c216174
Author: Thomas Schank <DrTom@schank.ch>
Date:   Fri Oct 11 08:00:10 2013 +0200

    Removed forgotten binding.pry, merde

commit 80fa04b18d261cdac68f4e750936a8082c1a394c
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 19:09:04 2013 +0200

    Fix: more defensive (hmmmm) set_meta_data method; allows empty hash e.g.

commit baf83e879beed6edcdf853a1f7725bb8d10381c9
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 18:32:44 2013 +0200

    Oooops, should have been "if" instead "unless" when creating meta_data

commit 61558febd7a3e3effa2c2b21308c91cbe76f8be9
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 18:03:49 2013 +0200

    Fix case when not deleting existing for apply to all

commit 917c929b3a13133f101e6d916ad0925bc3b6e0bc
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 16:38:47 2013 +0200

    Fix filter sets controller

commit cfcfb0c582fecf56b72f806efe695e2c750e7e91
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 16:16:40 2013 +0200

    Fix filter_sets_controller

commit 4300bfad0f9e0e10d4b7c0114fd076a434c313cc
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 16:16:24 2013 +0200

    Fix meta_data_controller

commit 8ff4574106f2fbba39bc4311cf167b3508476544
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 15:53:09 2013 +0200

    Fix sorting_spec

commit 9d59c49a6e16c5810a3430669944e693d8b9bbeb
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 15:46:02 2013 +0200

    Fix meta_data_spec

commit b65b089ad5bf94417fb6cf202fdfce52d7f62e05
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 13:33:50 2013 +0200

    Fix some stuff in the meta_data_controller

commit a91fd9490b2152c5a948bc0110f407f12c2bfabb
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 13:18:34 2013 +0200

    Fix filter_set_spec

commit 7fe9edd6c962191c9f08aa5327b1e17d843de3ca
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 13:13:17 2013 +0200

    Fixed media_entry_spec

commit c123a5e3bfbaabf52cb70bf2411963feda5a3d33
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 13:09:40 2013 +0200

    Fix media_resource_spec

commit f891e0eaa006b0d4fa379da5e336ed8ffcd53a67
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 13:03:22 2013 +0200

    Reenabled the hack in the MetaDatum initializer

    and adjust it

commit fd525f273b8afde5f057f5ee7c391c744816e6d4
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 12:58:49 2013 +0200

    Fix title_meta_datum_spec

commit 20b443d154cf1eec62316531b7f3e817ab8143ad
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 12:57:57 2013 +0200

    set_meta_data accepts hashes with string keys to

commit 5a8616cd960401e7157f33ffa7462e82fedaac15
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 12:49:03 2013 +0200

    Fixed meta_data creation part of typo_madek_player_plugin_request_spec;

    reading is still broken it seems to rely on our hack

commit 6bb2ad66a1e3f731e1beaa89eac0260d55afdb29
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 11:49:19 2013 +0200

    Added get_meta_datum_class to MetaKey instance

commit 18e2a32a9a299f095967e250f6685605b9035902
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 11:42:46 2013 +0200

    Fix spec meta_datum_keywords_spec

commit 12fb938964e6d24703e090d34fad7c7a893135fa
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 11:42:35 2013 +0200

    Fix set_meta_data

commit 5baa137ff7a71d439ea198663e283ec97bdeccf4
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 11:19:31 2013 +0200

    Removed outdated spec from meta_datum_spec

commit d814c2dc4a41573e4a840d5b9976f99c0c92c8cd
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 10:53:57 2013 +0200

    Fix person spec by using set_meta_data

commit 68df204e2586ef4a9e6a0b52fdf6fcaa51028f7d
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 10:52:55 2013 +0200

    Use set_meta_data instead accept through update_attributes;

    Removed alias chain

commit 1de76faa5776cb0c9dc710696c2ab493b419bb43
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Oct 10 10:51:17 2013 +0200

    Removed magic in MetaDatum creation

commit d40696484d68a67db1bd134a140213ef8f857d1a
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Oct 9 15:41:00 2013 +0200

    Disable accept_nested_attributes_for :meta_data