Replaced subprocess with os.remove/rename
Revert "Fixed instructions to match change made earlier"

This reverts commit 39767e194f148900cd3282cbd356604c1915fb4d.
Merged TkTech's cleanup/revamp
Merge pull request #1 from TkTech/master

Merge to close pull request
Revert "Cleanup"
Merge pull request #2 from Antrikshy/revert-1-master

Revert "Cleanup"
Revert to version before TkTech's contributions
Manual revert to TkTech's changes
Try to find 'ebook-convert' (from Calibre) and use it if KindleGen is not in current directory.

It gives preference to KindleGen over ebook-convert
Merge pull request #3 from rogeliodh/master

Fallback on Calibre's ebook-convert if KindleGen not found
Now enhanced with rogeliodh's Calibre support

And other enhancements.
Updated .gitignore to fix unnecessary conflict
Fix all of the PEP8 issues in cli.py introduced by merging with upstream.
Stop leaking file handles.