fixes and changes

[tommyka1]

• added configuration option "pause_on_idle" (default: True) that can be set to false in the case that the user wants the script to be running while they're not active on their computer (e.g while studying).
• fixed script incorrectly showing reward as $ for studies that paid out in £.
• fixed "Waiting for study..." console status not reappearing upon resuming study search.
• fixed pip error while trying to install playsound on most systems (Issue #150 on playsound repository).
• fixed module error while trying to run the script due to having a version of blinker higher than 1.7.0 (selenium-wire only works with 1.7.0 and lower).
• modified script to keep searching for studies after attempting to join a study that returned an error code.