Fix translated messages in WinRT-plugin.

Use plural form, remove white space from the messages,
use double quotes for file names. Use the winrtrunner.exe
only in messages about the file not being found.

Change-Id: I5d5ffc2ffc6b6dc86c97327e6f47c6e5c0b2ef11
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>