Expose channel snapshot manager blob generation

These functions are already used in one branch (jrose's parking branch)
and will soon be used in other branches as well.


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@385522 f38db490-d61c-443f-a65b-d21fe96a405b
Fix documentation.

git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@385548 f38db490-d61c-443f-a65b-d21fe96a405b