Update es.po

Improve translation and fix some typos.
Merge pull request #119 from Yajo/patch-1

Update Spanish translation
Fix gstreamer change in src/Makefile.am
Replace EggListStore with GtkListStore
Reorganize preferences dialog
Update screenshot in README.md
Update and review .po files
Updatate .po files
Update Polish translation
Update German translation
Update Spanish translation
Fix taking long break too often
Release version 0.10.0