downgraded rest-client to 1.6.8 to fix issue with ffi on windows

Gemfile.lock

@@ -6,7 +6,7 @@ PATH
       launchy (>= 0.3.2)
       multi_json (>= 1.10)
       netrc (>= 0.10.0)
-      rest-client (>= 1.7.3)
+      rest-client (>= 1.6.0)
       rubyzip (>= 0.9.9)
 
 GEM
@@ -28,26 +28,22 @@ GEM
       safe_yaml (~> 1.0.0)
     diff-lcs (1.2.5)
     docile (1.1.5)
-    domain_name (0.5.23)
-      unf (>= 0.0.5, < 1.0.0)
     excon (0.45.1)
     fakefs (0.6.7)
     heroku-api (0.3.23)
       excon (~> 0.44)
       multi_json (~> 1.8)
-    http-cookie (1.0.2)
-      domain_name (~> 0.5)
     json (1.8.2)
     launchy (2.4.3)
       addressable (~> 2.3)
-    mime-types (2.4.3)
+    mime-types (1.25.1)
     multi_json (1.11.0)
     netrc (0.10.3)
     rake (10.4.2)
-    rest-client (1.8.0)
-      http-cookie (>= 1.0.2, < 2.0)
-      mime-types (>= 1.16, < 3.0)
-      netrc (~> 0.7)
+    rdoc (4.2.0)
+    rest-client (1.6.8)
+      mime-types (~> 1.16)
+      rdoc (>= 2.4.2)
     rr (1.1.2)
     rspec (3.2.0)
       rspec-core (~> 3.2.0)
@@ -73,9 +69,6 @@ GEM
       tins (~> 1.0)
     thor (0.19.1)
     tins (1.3.5)
-    unf (0.1.4)
-      unf_ext
-    unf_ext (0.0.6)
     webmock (1.21.0)
       addressable (>= 2.3.6)
       crack (>= 0.3.2)

heroku.gemspec

@@ -24,7 +24,7 @@ Gem::Specification.new do |gem|
   gem.add_dependency "heroku-api",     ">= 0.3.19"
   gem.add_dependency "launchy",        ">= 0.3.2"
   gem.add_dependency "netrc",          ">= 0.10.0"
-  gem.add_dependency "rest-client",    ">= 1.7.3"
+  gem.add_dependency "rest-client",    ">= 1.6.0"
   gem.add_dependency "rubyzip",        ">= 0.9.9"
   gem.add_dependency "multi_json",     ">= 1.10"
 end