* defaults/main.yml: adds analytics schedule variables for configuring the AnalyticsSeedJob, with all analytics tasks enabled by default.
* templates/seed_job_template.xml: use updated analytics seed job config and description
* tasks/main.yml: generates a hashed password for the jenkins user, and adds jenkins-auth and create-seed-job tags.
* README.md: documents seed job parameters and jenkins auth change

This jenkins instance will perform following tasks:

* Set up authentication using Jenkins Unix Auth Realm
* Set up administrative user
* Load credentials from a JENKINS_ANALYTICS_CREDENTIALS variable
* Checkout seed job repository
* Launch seed job to populate Jenkins with analytics Jobs