Removing Dependency from SDK Core Project

- Copied files required for Rest API SDK
- Removed PPApiContext and directly connected APIContext with PPConfigManager
- Removed duplicate data storage of configuration and credentials.
- Code Style Fixes
- Remove build.xml file as it is not required anymore
- Updated the samples
- Updated the documentations

lib/PayPal/Exception/PPConfigurationException.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace PayPal\Exception;
+
+/**
+ * Class PPConfigurationException
+ *
+ * @package PayPal\Exception
+ */
+class PPConfigurationException extends \Exception
+{
+
+    /**
+     * Default Constructor
+     *
+     * @param string|null $message
+     * @param int  $code
+     */
+    public function __construct($message = null, $code = 0)
+    {
+        parent::__construct($message, $code);
+    }
+}

lib/PayPal/Exception/PPConnectionException.php

@@ -0,0 +1,68 @@
+<?php
+
+namespace PayPal\Exception;
+
+/**
+ * Class PPConnectionException
+ *
+ * @package PayPal\Exception
+ */
+class PPConnectionException extends \Exception
+{
+    /**
+     * The url that was being connected to when the exception occured
+     *
+     * @var string
+     */
+    private $url;
+
+    /**
+     * Any response data that was returned by the server
+     *
+     * @var string
+     */
+    private $data;
+
+    /**
+     * Default Constructor
+     *
+     * @param string $url
+     * @param string    $message
+     * @param int    $code
+     */
+    public function __construct($url, $message, $code = 0)
+    {
+        parent::__construct($message, $code);
+        $this->url = $url;
+    }
+
+    /**
+     * Sets Data
+     *
+     * @param $data
+     */
+    public function setData($data)
+    {
+        $this->data = $data;
+    }
+
+    /**
+     * Gets Data
+     *
+     * @return string
+     */
+    public function getData()
+    {
+        return $this->data;
+    }
+
+    /**
+     * Gets Url
+     *
+     * @return string
+     */
+    public function getUrl()
+    {
+        return $this->url;
+    }
+}

lib/PayPal/Exception/PPInvalidCredentialException.php

@@ -0,0 +1,36 @@
+<?php
+
+namespace PayPal\Exception;
+
+/**
+ * Class PPInvalidCredentialException
+ *
+ * @package PayPal\Exception
+ */
+class PPInvalidCredentialException extends \Exception
+{
+
+    /**
+     * Default Constructor
+     *
+     * @param string|null $message
+     * @param int  $code
+     */
+    public function __construct($message = null, $code = 0)
+    {
+        parent::__construct($message, $code);
+    }
+
+    /**
+     * prints error message
+     *
+     * @return string
+     */
+    public function errorMessage()
+    {
+        $errorMsg = 'Error on line ' . $this->getLine() . ' in ' . $this->getFile()
+            . ': <b>' . $this->getMessage() . '</b>';
+        return $errorMsg;
+    }
+
+}

lib/PayPal/Exception/PPMissingCredentialException.php

@@ -0,0 +1,37 @@
+<?php
+
+namespace PayPal\Exception;
+
+/**
+ * Class PPMissingCredentialException
+ *
+ * @package PayPal\Exception
+ */
+class PPMissingCredentialException extends \Exception
+{
+
+    /**
+     * Default Constructor
+     *
+     * @param string $message
+     * @param int  $code
+     */
+    public function __construct($message = null, $code = 0)
+    {
+        parent::__construct($message, $code);
+    }
+
+    /**
+     * prints error message
+     *
+     * @return string
+     */
+    public function errorMessage()
+    {
+        $errorMsg = 'Error on line ' . $this->getLine() . ' in ' . $this->getFile()
+            . ': <b>' . $this->getMessage() . '</b>';
+
+        return $errorMsg;
+    }
+
+}