Adds CONTRIBUTING.md

.gitignore

@@ -1,8 +1,4 @@
 Business-PayPal-API-*
-META.yml
-Makefile
-Makefile.old
+auth.txt
 blib
 pm_to_blib
-MANIFEST
-MANIFEST.bak

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# SANDBOX TESTING
+
+To install this module type the following:
+
+   perl Makefile.PL
+   make
+   WPP_TEST=auth.txt make test
+   make install
+
+Please notice that this module requires you have several things before
+you can test it:
+
+  - a sandbox personal PayPal account
+  - a sandbox business PayPal account
+  - API credentials (either a certificate or signature)
+  - auth.txt, which contains your API credentials
+
+Read PayPal's and this module's documentation to learn more about how to
+acquire PayPal sandbox credentials.
+
+If you do not set the WPP_TEST environment variable, sandbox tests will be
+skipped.
+
+The format of the authentication tokens file defined by WPP_TEST may be found
+in the Business::PayPal::API documentation under "TESTING". Sample auth.txt
+files may be found in 'auth.sample.3token' and 'auth.sample.cert' in this
+distribution.