Fax-Header and Fax-Ident headers now can be sent into the FS with the originate cmd
Modifications after code review.  Pulled changes outs of ecallmgr_fs_xml.erl and placed the new originate headers into to the SPECIAL_CHANNEL_VARS in ecallmgr.hrl  Made modifications to remove the freeswitch leaky abstractions into kazo
Misspelling in the headers for Fax-Identity-Number
KAZOO-434: fix http response headers for latest cowboy req