Added support for Strings and IPV6 adddress in option vendor-spec
fixed parameter type
Merge branch 'master'
Tweaking to Hernan's patch:

 - Newly added and previous (string) construtor were broken, fixed
 - Added unit-tests for existing and new constructors
 - Tweaked SrvParser.y a bi (address is now printed)
 - Updated User's Guide
 - CHANGELOG & AUTHORS updated