Proposal: Deprecate Python 3.4 Support

[makiftasova]

Motive:

• most major GNU/Linux distributions have Python 3.5 or newer in their package repos
• some bot dependecies (e.g. telepot) deprecated their Python 3.4 support

Suggestions:

• deprecate Python 3.4 support and notify users with a message on bot start
• update source code to use new async/await syntax

[nylonee]

Probably also worth noting that the telesync plugin in v3 of the bot will not run on python 3.4