Fixes & enhancements: fix deprecation warning on Python versions newer than v3.6 & support breaking of loop with CTRL-C with no exceptions

[Abdallah-Abdelazim]

Each commit in this PR describes a change I made. The changes I made are:

• Add python shebang line to allow easy running from a terminal with ./main.py [output_file] instead of python3 main.py [output_file].
• Add execute permission to main.py.
• Fix deprecation warning DeprecationWarning: There is no current event loop on Python versions newer than v3.6.
• Support breaking out of the loop with CTRL-C with no exceptions as it previously was printing an ugly exception to the terminal.
• Update README.md to add a note on how to install bleak package to help people with no Python experience.

[manister7]

Could we use this repo for python > 3.6 now???

[mrsteve0924]

nobody actively working on merging commits?