Don't use whitespace before punctuation in pitivi messages

Submitted by Christian Rose `@menthos`

Assigned to Christian Rose @menthos

It seems many messages in pitivi currently are like these examples, and use a whitespace before the colon:

#: pitivi/ui/elementsettingsdialog.glade.h:1
msgid "<b>Author :</b>"

#: pitivi/ui/elementsettingsdialog.glade.h:2
msgid "<b>Description :</b>"

#: pitivi/ui/encodingdialog.glade.h:2
msgid "Output File :"

#: pitivi/ui/exportsettingswidget.glade.h:22
msgid "Audio Codec :"

#: pitivi/ui/projectsettings.glade.h:2
msgid "Description :"

In proper English, a whitespace should not be used before punctuation, that is, before a comma, period, exclamation mark, colon, etc.

Please remove the whitespaces, so that the messages will be:

"Description:"

etc.