Merge pull request #2 from sebastien-villemot/master

Update French translation
experimental switch to openweathermap
Update Readme.md due to upload of openweathermap-branch.
Update Readme.md (build instructions, typo)
Pull README.md from openweathermap-branch.
Use different timers to update actual weather and forecast (save bandwidth on owm-server); minimal update interval is 10 min
update installation instructions; Debian packages available
Pull README.md from openweathermap-branch (update installation instructions; Debian packages available)
Use constants for URL's, use Soup methods to build the request-string
Format fixes
Use toLocaleFormat, to format time; fix for 12h time formats
Use toLocaleFormat, to format time; fix for 12h time formats
Always fetch 10 days of forecast-data.
Fix timers in stop-method
add missing comma
Readd shell-version 3.6
Readd shell-version 3.6
Add possibility to use personal API key from openweathermap.org
Explicitely state, that glib2 development packages are need for build the extension
Do not use deprecated Soup.SessionAsync .