Small changes on BitBucketConverter.py to compile with python 3.7.3

[gerdablum]

I tried to run the converter python script, as the online converter is down currently.
Python version 3.7.3, OS Version: Raspbian GNU/Linux 10 (buster)

There were a few issures I run into:

1. dependency pycurl was missing. In order to install it i needed to install some system libraries:

 sudo apt install libcurl4-openssl-dev 
 sudo apt install libssl-dev

after that I was able to install pycurl via pip3 install pycurl

2. script still did not compile because of a few typos (propably mixups between python 3 and python 2).
   I did some minor changes which I propose in this PR

After the changes I was able to run the script successfully with python 3