Widgets / Editing metadata related resources (#1255).

http://trac.osgeo.org/geonetwork/wiki/proposals/relatedResource

Squashed commit of the following:

commit 3ef7ab9ef47838cddb1ddfdf0bf47b5389d88828
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Mon Apr 15 09:21:57 2013 +0200

    Widgets / relation manager / Add support to set thumbnail description. Improve no preview image.

commit e37db043190a86baaa047150f74895321e5b9247
Merge: 087c72f d87c573
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Mon Apr 15 08:49:25 2013 +0200

    Merge remote-tracking branch 'upstream/master' into improvement/metadata-relation

commit 087c72f8b181d8449a7d9109fb16c774def116cd
Merge: 60f2289 d52f372
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Thu Apr 11 15:20:16 2013 +0200

    Merge remote-tracking branch 'upstream/master' into improvement/metadata-relation

    Conflicts:
    	web/src/main/webapp/WEB-INF/data/config/schema_plugins/iso19139/process/update-srv-attachDataset.xsl

commit 60f2289c2f74015be0b29c0cefc09ed3e3e090b3
Merge: 3b14743 88a2ca4
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Wed Apr 10 08:00:18 2013 +0200

    Merge remote-tracking branch 'upstream/master' into improvement/metadata-relation

commit 3b1474302bb2b6f9b8d29aaebba40229610c1515
Merge: 57fc450 7fb26a5
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Tue Apr 9 08:12:51 2013 +0200

    Merge remote-tracking branch 'upstream/master' into improvement/metadata-relation

commit 57fc45005a247d85061d07366aef92b22cf71761
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Tue Apr 9 08:11:09 2013 +0200

    Add service for resource upload/removal.

commit b32fe9eaf3e76185c802ecfb317671f3912bb430
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Wed Apr 3 15:54:42 2013 +0200

    Widgets / relation manager / properly handle uploaded resources.

commit bb162db4342eab4af237c03d73599172b2fb78c1
Author: François Prunayre <fxprunayre@gmail.com>
Date:   Wed Apr 3 11:50:21 2013 +0200

    Widgets / Editing metadata related resources (#1255).
Merge remote-tracking branch 'origin/master'