Register areCredentialsValid as a sensitive logging method
Register areCredentialsValid as a sensitive logging method

As the method stores a username and password in clear text, if an
exception is thrown during its execution the password may be written to
the log file. This change prevents that from happening.

owncloud/core,owncloud/core,owncloud/core,phil-davis/core,owncloud/core,owncloud/core