This commit fixes the following broken --getter option:
when systemd-journal-remote is called with --getter option,
it causes the error meesage "Zero sources specified" and
the getter command will not be called.
When --url option is specified, e.g. --url='http://some.host:19531/entries'
retrieved remote journal entries will be stored to
/var/log/journal/remote/remote-some.host.journal
Currently, --url option supports the only form like http(s)://some.host:19531.
This commit adds support to call systemd-journal-remote as follwos:
systemd-journal-remote --url='http://some.host:19531'
systemd-journal-remote --url='http://some.host:19531/'
systemd-journal-remote --url='http://some.host:19531/entries'
systemd-journal-remote --url='http://some.host:19531/entries?boot&follow'
The first three example result the same and retrieve all entries.
The last example retrieves only current boot entries and wait new events.