Update bytearrays-and-bytestrings.ipynb

Line 18, instruction 3 - changed word from 'it' to 'test'

Line 42 removed an extra 'h' in 'this'

Line 139 This code did not seem to produce the correct output therefore I could not proceed with any further code.
Merge pull request #2 from bugzPDX/master

Update bytearrays-and-bytestrings.ipynb - Neither issue was Python version-dependent