Fix formatting to make it PEP8-compliant
Add logging support
Fix bug in handling multiple WWW-Authenticate headers

When the server offered multiple authentication methods:

WWW-Authenticate: Negotiate
WWW-Authenticate: Basic realm="My Realm"

requests-negotiate failed to parse the resulting header.  This patch fixes
the issue, and also uses named matches to make the logic more clear.
slightly easier to read and also rfc7235 compliant.
Turn regex debugging print statement into logger.debug() call
Fix "Keytab /etc/krb5.keytab is nonexistent..." error on Ubuntu 14.04 LTS

The Kerberos libraries that exist in Ubuntu 14.04 require that the credential
usage type (C_ACCEPT or C_INITIATE) is specified in the Credential()
constructor.
Merge pull request #1 from rb12345/master

Add logging support, fix bug with multiple WWW-Authenticate headers and support for slight oddness with Kerberos on Ubuntu 14.04 LTS