AutoMigration Implementation

[keronei]

This contains changes with guides that utilise efficient ways to migrate databases.

Since Room version 2.4.0-alpha01, Room supports automated migrations which involves less work and cleaner code.

All the migrations have been implemented in AutoMigration, this makes it easy to work with other android libraries that require updated dependencies.

The README.md has also been updated to reflect the current changes, while preserving the original guides for reference purposes.

To verify that the migrations are working as expected, all tests have been ran and no errors were encountered.

[realityexpander]

This is great and should be merged in!