Ruby 530 kerberos on JRuby

This pull request consists of a java extension for using the java sasl package. The jar is checked into the repo but you can compile it by invoking the jsasl rake task:

    rake compile:jsasl

There are some additions to the authentication module in order to allow authentication using the java extension, in addition to a module called Sasl / GSSAPI that uses the java extension.

The URI parser has been updated to include GSSAPI authentication options, gssapiservicename and canonicalizehostname. (Plus tests)

In order to test, you must either:

1. Use JRuby
2. Have a keytab file
3. Set up a SASL config file that references a keytab file
4. Set the following environment variables:
	- MONGODB_GSSAPI_USER
	- MONGODB_GSSAPI_HOST
	- JAAS_LOGIN_CONFIG_FILE
        - MONGODB_GSSAPI_REALM

or

1. Use JRuby
2. Run kdestroy to get rid of any existing tgts
3. Run kinit with your credentials
4. Set the following environment variables:
	- MONGODB_GSSAPI_USER
	- MONGODB_GSSAPI_HOST
        - MONGODB_GSSAPI_REALM
5. Run the tests and enter in the user and host names in the command prompts.