Merge pull request #56 from sinemetu1/master

Fixed a few issues
Merge pull request #58 from sinemetu1/master

Added caching of downloaded files.
Update README.md

Being explicit about the usage of python 2 because trying to install mozregression with python3 and corresponding pip will fail.
Merge pull request #65 from amitavmohanty01/patch-1

Update README.md
Update README.md

Update spacing in example output