Update ssl reset script

Use puppet cert generate instead of requiring the user to ctrl-c
Back up certificates with timestamps so it's non destructive
Clarify the agent cert regeneration message
Add a file_line resource (ugh) to fix the session lifetime.
Remove redundant 'mkdir -p' since next line does it, too.
Merge pull request #327 from fnaard/ticket/TRAINVM-118/remove_redundant_mkdir_p

Remove redundant 'mkdir -p' since second line does it, too.
Merge pull request #326 from klynton/session-timeout

Add a file_line resource (ugh) to fix the session lifetime.
Merge pull request #325 from binford2k/update_ssl_reset_script

Update ssl reset script