Fix a new error in scrapping explanation
Update python-telegram-bot library
Don't use hdurl for sending images

Sometimes the image is too big and the bot library fails due to that.
Update explanation consistently with release
Add apod function to the Telegram bot
Refactor code

It creates the Apod class called from every bot and also useful functions. It
seems to be a (bit) decent library.
Make the first version of the Telegram bot
Improve instructions for installation
Scrap description with links from web page

The API does not give the description with the links, so I had to write a
scrapping tool to get it from the main page.
Deal with invalid dates correctly
Download and save video

It checks the media type and download accordingly.