Release v1.1.12

This release fixes a potential security issue. In case the password started with the `@` symbol, curl would have tried to either transfer a file named like. Transferring such a file would be a problem on it's own. But even if not, the exception message that informs about the failure contains the password in plaintext (only the `@` missing). If those messages are passed to the user without further checks, the password would have been leaked. Same for storing the error messages into log-files.

An exemplary error message for the password `@password` is:

> Curl error: (#26) couldn't open file "password" `CODE_CURL_ERROR`

This has been fixed now. Instead the login now works or the following exception is given:

> Login unsuccessful. `CODE_LOGIN_ERROR`.



- Fix that allows "@" ("\x40") as first character in passwords. Fixes a
  security issue. See Issue #15
- Fix error message on empty email address. Introduced in 7a12003