Merged in Excercise (pull request #3)

Remove redundant code

Use enum for strategy implementation

Hide background while exercise

minor fixes

Move strategy pattern implementation in separate package

Merged in voice (pull request #4)

Count progress

Add exercise key

Initial voice support for exercises

get rid of extra cors config

get rid of unused dependencies. send credentials every time

set up frontend env variables

initial commit

Merged in Handle_duplicates (pull request #2)