Use new branch of the paypal gem

This uses the `2-1-0-stable` branch of the paypal gem. It's the 2-1-stable branch plus a couple of old OFN modifications (from 2-0-stable), plus a minor modification to the gemspec to allow it to be used with spree_core `2.1.0`

Gemfile

@@ -27,7 +27,7 @@ gem 'spree_i18n', github: 'spree/spree_i18n', branch: '1-3-stable'
 # Our branch contains two changes
 # - Pass customer email and phone number to PayPal (merged to upstream master)
 # - Change type of password from string to password to hide it in the form
-# gem 'spree_paypal_express', github: "openfoodfoundation/better_spree_paypal_express", branch: "2-0-stable"
+gem 'spree_paypal_express', github: 'openfoodfoundation/better_spree_paypal_express', branch: '2-1-0-stable'
 gem 'stripe'
 
 # We need at least this version to have Digicert's root certificate

Gemfile.lock

@@ -4,6 +4,15 @@ GIT
   specs:
     custom_error_message (1.1.1)
 
+GIT
+  remote: https://github.com/openfoodfoundation/better_spree_paypal_express.git
+  revision: e28e4a8c5cedba504eea9cdad4be440d277d7e68
+  branch: 2-1-0-stable
+  specs:
+    spree_paypal_express (2.0.3)
+      paypal-sdk-merchant (= 1.106.1)
+      spree_core (~> 2.1.0)
+
 GIT
   remote: https://github.com/openfoodfoundation/spree.git
   revision: 95d3ccb32f2e4016d0fc73f39446d1739da56c50
@@ -478,6 +487,11 @@ GEM
       activerecord (>= 4.0, < 6.1)
     parser (2.7.0.2)
       ast (~> 2.4.0)
+    paypal-sdk-core (0.2.10)
+      multi_json (~> 1.0)
+      xml-simple
+    paypal-sdk-merchant (1.106.1)
+      paypal-sdk-core (~> 0.2.3)
     pg (0.21.0)
     polyamorous (0.6.4)
       activerecord (>= 3.0)
@@ -752,6 +766,7 @@ DEPENDENCIES
   spinjs-rails
   spree_core!
   spree_i18n!
+  spree_paypal_express!
   stripe
   test-unit (~> 3.3)
   timecop