Adds the contact exporter script to Librem5-goodies

This script allows to export all contacts in all of evolution adressbooks to a single vcard or csv file.

What works:

• All the contacts from all the addressbooks in Evolution Data Server will be exported to a single file (vcard or csv) in the home directory with a timestamp.
• Script should work from both a yad gui and from a terminal, see the usage function to see how to use from a terminal or just run the script with --help

What is not implemented:

• There are no notifications
• The application does not automatically close when the export is done
• There are no success nor error messages
• There is no support a the moment to select a specific addressbook nor a specific contact
• App tray icon is a totally random and ugly icon

Notes:

This script uses functions and the only way I found to invoke a function in a yad button was to export the functions first and then to execute them from the button.

This does not use syncevolution, but the binary: addressbook-export from /usr/libexec/evolution-data-server

./usr/libexec/evolution-data-server/addressbook-export -l can list the different addressbooks.

Like this:

"1464341145.1743.5@nelly","Contacts",96
"system-address-book","Personal",178
"1468318619.3018.2@nelly","test transfer",61

And selecting a specific address book should be possible with something like:

./addressbook-export 1468318619.3018.2@nelly --format=vcard --output=~/contacts-backup-"$(date +%Y-%m-%d-%H%M%S)".vcf