Clean up attributes, metadata, README

* Set metadata to point to EverTrue
* Add `nginx` as a dependency to metadata
    * The `nginx_proxy` recipe needs it, so it’s
a dependency
* Clean up attributes
* Rewrite README:
    * Represent attributes more cleanly
    * Set a better example for using the cookbook
Switch license to Apache 2.0

OSS code is OSS
Clean up nginx_proxy recipe

Consistency is key

* Align resource attributes’ arguments
* Use strings for modes
Move url_version attribute into recipe

Dynamically assigned attributes like these are best
set inside recipes.

In this way, we could change the version attributes
in a wrapper cookbook, and not need to also set
this attribute.
Clean up default recipe

* Align resources’ attributes’ arguments
* Remove potentially inaccurate comment
    * Depending on attribute settings, it might not be
installed in `/opt`
Upgrade to Archiva 2.1.0
Fix dependency versions in metadata
Fix url attribute’s attribute consistency
clean up nginx proxy part 2
Ensure node attributes are accessed consistently
Add ignore files
Add Berkshelf, RuboCop, Test Kitchen, etc.

* Config to test current LTS Ubuntus & Debian 6
* RuboCop config to set sane expectations
* Base Berksfile
* Rakefile with handy test tasks
Add Travis CI style & unit testing
Refactor nginx_proxy recipe to include default

Can't really have one without the other, and this
ensures that the `service[archiva]` resource is properly
available in the `nginx_proxy` recipe
Add CHANGELOG
Add ChefSpec tests, use bleeding-edge ark

Need the bleeding edge ark so we have access to the ChefSpec matchers
that haven't landed in a released version yet.

Courtesy of that unreleased ark, some breaking changes to the LWRP:

* Add ark prefix_home to deal w/ ark changes
Properly use archiva home attribute for paths

Absolute paths means broken code if the attribute
changes elsewhere.

This ensures we are consistent in the attribute usage.
Use chef-sugar to guard file deletion

Less is more
Add ServerSpec tests
Add Travis integration testing