The default location which is used when the
PluginParemeter "googlemaps.cachefolder" is not specified
should be ~/.cache/googlemaps on Linux or
/user/<name>/appdata/local/cache/googlemaps on Windows.
This patch moves the cache to the default system location
where we store the printing templates, cloudstorage and the
default user XML file.
Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>