Fixes #3569, #3210 - Use port from foreman_url for templates

[REFACTOR] fixes #2967 - refactored Fact Importer

Based on Dmitri Dolguikh <dmitri@appliedlogic.ca> original patch.

- renamed original fact_importer class to fact_parser class
- moved fact handling logic to its own fact_importer class
- fact importer now assumes single-value facts...

fixes #2741 - rails 3 syntax

fixes #3190 - Fix STI auditable_type - Audit should say updated Location/Organization rather than updated Taxonomy and ComputeResource should not use STI class

fixes #3202 - PG constraints deferred and change destroy_all to delete_all

Fixes #3144 Remove user_id and inherited_from

Fields user_id in model User and inherited_from in model UserRole are
absolutely superfluous as they are not being used anywhere and result in
unnecessary lines of code and clutter in the database, which contains...

Fixes #3130 - Use the standard CentOS mirror

fixes #2400 continuation - match all host STI classes when finding orphaned records

fixes #2400 migration to remove orphaned records and add foreign keys constraints to database tables

fixes #1719 - Add support for GCE