Introduce support for HTTP connections. Use "HTTPS" in the config file
to enable/disable (default is enabled). The option modifies the prefix
of the host name to "http://" when disabled, rather than always using
"https://" with no option to change.
httplib2 automatically handles URLs beginning with either http or https.
Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>
