validity check, replace_otp in personalSettings

- fixed validity check for token to use _OTP_VALID_CHARS_
- run create_otp only when delete_otp was successful on replace_otp
- check whether given token is already base32 and save decoded string to enable users to provide token created by other otp applications

Signed-off-by: Andrwe Lord Weber <lord-weber-andrwe@andrwe.org>
added CHANGES, describe undocumented changes of last commit

- CHANGES lists all differences of this branch to the original app

undocumented changes of commit 22c707caaa51db57f03bb6e94bff7917b6c72b0c
- added some TODOs
- added still unused writeLog function
- added debug code to implement correct prefix pin check as multiotp declares a missing but required pin as unknown error
- added display of ErrorCounter on user_list
- fixed wrong string suplementation for userPin on user_list due to missing type casting

Signed-off-by: Andrwe Lord Weber <lord-weber-andrwe@andrwe.org>
pin check

- finished check for prefix pin
- removed debug code
- replaced error 99 of multiotp with default message "The OTP token was wrong" as it mostly is the issue

Signed-off-by: Andrwe Lord Weber <lord-weber-andrwe@andrwe.org>
removed notice for android apps & update TODO

- marked finished TODO as DONE
- removed notice for android apps to use base32 because all apps has to use it as default as stated on https://code.google.com/p/google-authenticator/wiki/KeyUriFormat

Signed-off-by: Andrwe Lord Weber <lord-weber-andrwe@andrwe.org>