Add UDDS attribute and refactor

Apologies for the large and hard to read PR--it should hopefully make the code more easy to read and navigate.

This PR adds UDDS as an attribute for UserDetails, along with a new class, PreauthUserDetailsProvider, which is an implementation of UserDetailsProvider for UW-Madison login.

Notable changes:

1. 'HTTP' is now assumed by default. This is the flag that can be passed to Preauth constructors for the 'HTTP' versions of attributes. Example: wiscEduPVI becomes HTTP_WISCEDUPVI.
2. UserDetailsProvider is an abstract class now, not an interface.
3. Constants used for header keys are much more consistent. Keys for UW-System login no longer have the FED_ prefix and you will get the correct key for your particular implementation (FederatedPreauth... vs. Preauth) by using static::<CONSTANT_NAME>. The only exception: UWMSN and UW-System differ on their name for 'PVI'--UWMSN uses "PVI" and UW-System uses "SPVI", so PVI is only a constant in PreauthUserDetailsProvider while FederatedPreauthUserDetailsProvider has an SPVI constant.
4. Namespace reorganization. Rather than lumping everything into the edu\wisc\doit namespace, the namespace structure is now much more like uw-spring-security. General classes now exist in the edu\wisc\doit\uwphps namespace, with local and preauth namespaces existing for the local and preauth implementations. This change necessitated the bump to 2.0.0.

Please review: @ahoffmann @weizhong-wang @KJOYNER

src/main/edu/wisc/doit/uwphps/local/LocalUserDetailsProvider.php

 <?php
 
-namespace edu\wisc\doit;
+namespace edu\wisc\doit\uwphps\local;
+
+use edu\wisc\doit\uwphps\preauth\PreauthUserDetailsProvider;
+use edu\wisc\doit\uwphps\UWUserDetails;
 
 /**
  * LocalUserDetailsProvider provides a developer with a {@link UWUserDetails} suitable for use in local development.
  */
-class LocalUserDetailsProvider implements UserDetailsProvider
+class LocalUserDetailsProvider extends PreauthUserDetailsProvider
 {
 
     /** @var string */
@@ -14,10 +17,11 @@ class LocalUserDetailsProvider implements UserDetailsProvider
     /**
      * LocalUserDetailsProvider constructor.
      *
-     * @param $filePath path to JSON file defining a local user.
+     * @param $filePath string Path to JSON file defining a local user.
      */
     public function __construct($filePath)
     {
+        parent::__construct(false);
         $this->filePath = $filePath;
     }
 
@@ -34,15 +38,15 @@ class LocalUserDetailsProvider implements UserDetailsProvider
         $attributes = json_decode($jsonString, true);
 
         return new UWUserDetails(
-            $attributes[UserDetailsProvider::FED_EPPN],
-            $attributes[UserDetailsProvider::FED_SPVI],
-            $attributes[UserDetailsProvider::FED_FULLNAME],
-            $attributes[UserDetailsProvider::UDDS],
-            $attributes[UserDetailsProvider::FED_EMAIL],
-            $attributes[UserDetailsProvider::SOURCE],
-            $attributes[UserDetailsProvider::ISIS_EMPLID],
-            $attributes[UserDetailsProvider::FED_FIRST_NAME],
-            $attributes[UserDetailsProvider::FED_LAST_NAME]
+            $attributes[static::EPPN],
+            $attributes[static::PVI],
+            $attributes[static::FULL_NAME],
+            $attributes[static::UDDS],
+            $attributes[static::EMAIL],
+            $attributes[static::SOURCE],
+            $attributes[static::ISIS_EMPLID],
+            $attributes[static::FIRST_NAME],
+            $attributes[static::LAST_NAME]
         );
     }