Non-Ascii emails are not readable

Example: A Crowd instance using Japanese language will continue using Ascii to create and send emails to users when the password is reset.

The Reset Password feature was fixed by changing class MailManagerImpl

Before:

private static final String MAILER_CONTENT_ENCODING = "text/plain;charset=\"us-ascii\";";

After:

private static final String MAILER_CONTENT_ENCODING = "text/plain;charset=\"UTF-8\";";