Added mrbgem's summary.
MODIFY
mrbgems/mruby-io/mrbgem.rake
mrbgems/mruby-io/mrbgem.rake
MRuby::Gem::Specification.new('mruby-io') do |spec|
spec.license = 'MIT'
spec.authors = 'Internet Initiative Japan Inc.'
+ spec.summary = 'IO and File class'
spec.cc.include_paths << "#{build.root}/src"

MODIFY
mrbgems/mruby-pack/mrbgem.rake
mrbgems/mruby-pack/mrbgem.rake
MRuby::Gem::Specification.new('mruby-pack') do |spec|
spec.license = 'MIT'
spec.authors = 'Internet Initiative Japan Inc.'
+ spec.summary = 'Array#pack and String#unpack method'
spec.cc.include_paths << "#{build.root}/src"
end

MODIFY
mrbgems/mruby-socket/mrbgem.rake
mrbgems/mruby-socket/mrbgem.rake
MRuby::Gem::Specification.new('mruby-socket') do |spec|
spec.license = 'MIT'
spec.authors = 'Internet Initiative Japan'
+ spec.summary = 'standard socket class'
spec.cc.include_paths << "#{build.root}/src"

Added mrbgem's summary.