Add german translation

[tofi86]

Add german translation files.

Yes/No buttons in Dialogs are still in French though, see #128 (comment)

[tofi86]

Dear maintainers: Please ping me a couple of days before the next public release / every public release after its feature-freeze so I can update the german language file in time!

[llemeurfr]

Thanks a lot Tobias, for these translations.
Note: I see that a TravisCI lint check has failed...
Ok, we'll ping you (as much as we can trigger our memory).
Don't hesitate to give us info about your use of Readium Desktop.

[tofi86]

@llemeurfr yeah, just noted a linting error. Will fix it.

[danielweck]

Hello Tobias, I believe Pull Requests must target the 'develop' branch, not 'master' (which is used to tag releases).

[tofi86]

Hi Daniel, alright, I changed target to develop. Travis running again, but shouldn't be a problem as master and devlop seem to be even. Will do that for the other PR's as well.

You could add a GitHub Contributing file to state this info.

[JayPanoz]

You could add a GitHub Contributing file to state this info.

See also PR templates e.g. the one for readium-css, with a checklist at the very beginning to make sure everything is OK. Not perfect but it’s at least another safety net.

[tofi86]

Thanks for merging!