dcache: alarms fix four small bugs

module dcache alarms

Four small bugs:

1.  alarm send:  if -s does not provide a path, the subsequent string operation throws array out of bounds.
2.  alarm definition toXML is not emitting the matchException node when the value is true rather than false (the default)
3.  the server logback file defines the MAIL appender reference after it uses it, which is not allowed.
4.  If an alarm has an id which permits duplicates, and the admin closes the alarm, but thereafter another of its type arrives, that alarm currently will not be visible unless show closed is selected.  The fix is to force the closed flag to false on duplicate arrival.

Target: master
Patch:  http://rb.dcache.org/r/5602
Require-notes: yes
Require-book: no
Request: 2.6
Acked-by: Tigran

RELEASE NOTES:

Fixes four small bugs.

1.  dcache alarm send:  if -s does not provide a path (e.g., "src://otfrid" rather than "src://otfrid/"), the subsequent string o$
2.  dcache alarm add * modify fail to record matchException = true because of a logic error in the XML emitter.
3.  the server logback file defined the MAIL appender reference after it uses it, which is not allowed.
4.  If an alarm has an id which permits duplicates, and the admin closes the alarm, but thereafter another of its type arrives, that alarm currently will not be visible unless show closed is selected.  The fix is to force the closed flag to false on duplicate arrival.