res_calendar_ews: Relax neon version check to work with 0.30 too.

Allow res_calendar_ews to work not only with libneon-0.29 but also
with 0.30.

ASTERISK-24325 #close
Reported by: Tzafrir Cohen

Review: https://reviewboard.asterisk.org/r/4068/
........

Merged revisions 425286 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@425287 65c4cc65-6c06-0410-ace0-fbb531ad65f3