Fix typo on line 486

Was "Add five zeros the front of the current zip " and is now "Add five zeros to the front of the current zip "
Merge pull request #659 from srt32/patch-1

Fix typo on line 486
Merge pull request #660 from pzula/master

Updating Ruby in 100 Minutes Arrays to show example usage
Merge pull request #661 from pzula/master

Adding IRB instructions to run simplified hash index on Ruby in 100 Minutes
Update typos in lines 1349-1353

Was, "Afterwards we actually send all the entire form letter content to the file object. The file object responds to the message puts. The file#puts is similar the Kernel#puts that we have been using up to this point."

is now, "Afterwards we actually send the entire form letter content to the file
object. The `file` object responds to the message `puts`. The
[file#puts](http://rubydoc.info/stdlib/core/IO#puts-instance_method) is similar to 
the [Kernel#puts](http://rubydoc.info/stdlib/core/Kernel#puts-instance_method)
that we have been using up to this point."
Merge pull request #663 from srt32/patch-1

Fix typos in lines 1349-1353
Fix codeclimate link to Tracks
Merge pull request #664 from mariusbutuc/patch-1

Fix codeclimate link to Tracks
Updating the instructions to Building an Identity, as a few people have accidently cloned the repository into their .ssh folders