Fix syslogtag parser to allow '/'

To allow logfiles have been written to /var/log/remote subdirs,
'/' should be allowed to pass with %syslogtag%

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>
Merge pull request #337 from bogdando/fix_rsyslog_consolidation

Fix syslogtag parser to allow '/'