connection: check for transaction before attempts to access objects in it

so Haraka doesn't crash
Merge pull request #549 from msimerson/connection

connection: check for transaction before attempts to access objects in i...
smtp_proxy: bug fix, defines an undefined variable
Merge pull request #550 from msimerson/smtpproxy

smtp_proxy: bug fix, defines an undefined variable
Prevent duplicate newlines in bounce message
Fix example and prevent leak FDs
Increase the default open file limit in Upstart script
Fix date format on bounce messages
Fix timeout when processing mail
Merge branch 'master' of github.com:baudehlo/Haraka
in_host_list: 3 changes:

1. read in config file in register, with a callback to reparse
   a) config file refreshes when altered
   b) regex only recompiled when changed (was every transaction)

2. when relaying=true, rcpt gets an automatic pass
   (before: relaying connections rejected at rcpt)

3. when relaying=true, mfrom host validated against in_host_list
      because by default, that's the sensible thing to do
host_list: documented behavior when relaying=true
host_list: documented behavior when relaying=true
in_host_list: load config at register with callback,

for relaying clients, only OK outbound recipients when MAIL FROM domain is local