Add support for more authentication methods

[dmranck]

TicketUtil currently supports:

• Kerberos for JIRA, RT
• Basic Auth for Redmine, Bugzilla

Add support for more authentication methods.

[Akasurde]

Can you please implement Basic Auth for JIRA ? Kerberos login is disabled on my JIRA instance.

[dmranck]

All tools support HTTP Basic authentication, while JIRA and RT also support Kerberos authentication. Look into if there are additional kinds of authentication we should be supporting in each tool.

[dmranck]

Possibly add authentication classes instead of the current implementation of just accepting a string for kerberos and a tuple for HTTP Basic auth.

Auth classes in Requests: http://docs.python-requests.org/en/master/user/authentication/

Previous idea for authentication classes: 30ba2f5
I like this idea, but think it should be generic across all tools, either in ticket.py or a separate auth.py file.