i18n : add spanish, italian, japanese, korean and portuguese translations

Adding new translation in spanish, italian, japanese, korean and
portuguese, for all strings from mediaelement-and-player.js
i18n : update german, simplified and traditionnal chinese translation

Update translations in german, simplified and traditionnal chinese , for
all strings from mediaelement-and-player.js
Update mep-feature-progress.js

Remove return false from time rail click/touch event to allow event bubbling
Skip back feature
Update mep-player.js

This is blowing up responsive design and players that are loaded dynamically. Because the parent container may be empty on load, race conditions exist that will override the height to the initial height of the parent, which may be something like 30px when the video has properly passed a height of something like 258px
Merge pull request #1337 from staylor/patch-2

Update mep-player.js
Merge pull request #1320 from matthillman/skip-back

Skip back feature
update on progress
skipback update
Merge pull request #1318 from dennyferra/master

Allow click/touch event bubbling on time rail
Merge pull request #1310 from jalios/master

i18n : add new translations and update existing one
pull update
i18n update
changed new target version number
merge