(maint) ignore .DS_Store files
(docs) ACL Access Rights Mask Addition

Provide a worksheet to allow folks to be able to add up access
rights mask values for those that would like granular values.
Merge pull request #44 from ferventcoder/add-acl-rights-addition-worksheet

ACL Access Rights Mask Addition Worksheet
(maint) Allow setting gem mirror via GEM_SOURCE env var
Merge pull request #45 from justinstoller/maint/master/config_gem_mirror

(maint) Allow setting gem mirror via GEM_SOURCE env var