Update README.md

Unified get_user_by_mac() letter case

Added online- and name- filter method for users

Fix dictionary indexing

Updated requirements.txt

Valid specific user check in the example.py

Readme fix

Updated 'write' function to set multi-key values

Read function return dictionary with multiple key

Added simple write block function

Added router state codes and getting peer mac function

Upgraded auth information updating

Removed magic number

Added block's ids constants for reading router's information

Updated README.md