Merge pull request #16 from shlinux/master

Update Chinese Translation
Use buttons instead of menus for locations, preferences and reload.
Update language files
Use icons on buttons instead of text as default.
(Temporarily ?) remove comaptibility for gnome-shell < 3.8
Fix bug #17 (arrow of menu-item that holds the locations not hidden when item is not expanded)
Move link to openweathermap.org into the buttons-menu to make the ui more compact.
Make sure button texts are shown in any case.
Fix St-CRITICAL because of accesssing the width of a BoxLayout before it was rendered.
Use coreect icon for refresh-button. Fixes #18 .
Keep the dialog open when changing locations.
Use pseudo-classes to differentiate between ltr and rtl, only use clutter textdirection to make source more clear.
Backport button-layout to 3.6 and 3.8 to make the ui smaller,
Rename styles from weather-something to openweather-something, rename (global) variables accordingly
Fix year of copyright
Added pt_BR, thanks Diego Neves
Updated language files.
Update Chinese translation files