Fix about_blocks koan

* Test on line 77 took a while to figure out

* lambda is some kind of block, with special
  properties, I think.
  
[#54145685]
Fix about_sandwich_code koan

* Learn useful methods to access files outside
  of the application.

* Concept of the sandwich is intriguing, but
  is there a solution to the repeated code?

* e.g. gems or other libraries with better 
  functionality.

[#54145687]
Merge pull request #19 from bayendor/54145685_about_blocks_master

Fix about_blocks koan

[Delivers #54145685]
Merge pull request #20 from bayendor/54145687_about_sandwich_code_master

Fix about_sandwich_code koan

[Delivers #54145687]