ignore for MacOS
tuning some params

change max word length to be over 4, otherwise there would be no need
to fill words with 5 or more chars.

change max_tmp_words to be 512 according to the python version ‘pymmseg’
use the new way of building

‘rake/gempackagetask’ has been deprecated and changed to
‘rubygems/package_task’

‘Gem::Builder.new().build’ changed to ‘Gem::Package.build’
detect brew

if brew is installed, there is no need to install with sudo
use the new way to build

‘rake/rdoctask’ has been deprecated and changed to ‘rdoc/task'
detect if brew installed

if brew is installed use the default options
update version