Change delimiter for ZED email scripts

When the ZED_EMAIL_INTERVAL_SECS="3600" option is set in zed.rc
configuration file then notification emails should be rate limited.

Rate limiting is accomplished by maintaining a colon delimited state
file which includes the device name. Unfortunately there are valid
device names which include a colon and therefore prevent the rate
limiting for working properly. For this reason the delimiter has
been changed to a semi-colon.

Signed-off-by: louwrentius <louwrentius@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
Closes #2645