add logging
use capistrano's strategy to deploy cookbooks
fix problems around :deploy_subdir and :copy_cache

(1) steup dedicated :copy_cache per cookbooks
(2) set :deploy_subdir as nil by default to override project's
    :deploy_subdir
(3) add :chef_solo_cookbooks_default_variables to clarify default
    settings for cookbooks
update comments and logging messages
use :chef_solo_repository_cache to generate path to the :copy_cache
release 0.1.2
Merge branch 'release-0.1.2'
Merge branch 'master' into develop
0.1.3git