AMI: Revert non-backwards compatible changes from earlier commit.

AMI: Revert non-backwards compatible changes from earlier commit.

* Reverted the change to astman_send_listack() to not use the listflag
parameter and always set the value to "Start" so the start capitalization
is consistent.  Unfortunately changing the case of a returned value is not
a backward compatible change so for now FAXSessions is going to have to
remain inconsistent with all of the other AMI list actions.

* Reverted the minor protocol error fix in action_getconfig() when no
requested categories are found.  Each line needs to be formatted as
"Header: text".

Caught by the testsuite.

ASTERISK-24049
........

Merged revisions 430528 from http://svn.asterisk.org/svn/asterisk/branches/13

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@430529 65c4cc65-6c06-0410-ace0-fbb531ad65f3