Convert IDN from ASCII to Unicode in Upload Dialog

Display IDN host names as Unicode in the FileUpload Dialog. This dialog
is shown when multiple ownCloud accounts are setup and a file is shared
with ownCloud.

Fixes #708.
Merge pull request #722 from ogasser/idn_share_fix

Convert IDN from ASCII to Unicode in Upload Dialog
Merge branch 'develop' into release-1.6.2