moved password changing operation to route PATCH/accounts/change-password/
rename POST/accounts/checkAccount to POST/accounts/check-password/
route PATCH/accounts/:account_id/ now only updates account's phone number and roles (isMentor/isMentee), other account settings relating updates can be done through route PATCH/account-settings/:account_id/
added tests for changing and checking account's password
Issue: #80
/accounts/change-password//accounts/checkAccountto POST/accounts/check-password//accounts/:account_id/now only updates account's phone number and roles (isMentor/isMentee), other account settings relating updates can be done through route PATCH/account-settings/:account_id/