* explained what pwd stands for
* added a section on spaces in file names
Made some tweaks based on the 1/2013 workshop

* added linebreak before irb command in step 2 - people blew past it
* added different line prompts - some installations had a different one
* explained control-C and that it could be used to exit
Merge pull request #21 from janetriley/master

IRB and command line updates after 1/2013 workshop