Downgrade rack-test to 0.6.3, to avoid breaking projects.

rack-test 0.7.0 introduces controversial changes, in particular about
body provided on DELETE requests:

rack/rack-test#132

Waiting for a solution there, we force the version of rack-test to
a version that is known for working on Enspirit projets.

examples/restful/Gemfile.lock

@@ -1,11 +1,11 @@
 PATH
   remote: ../..
   specs:
-    webspicy (0.2.0)
+    webspicy (0.2.1)
       finitio (~> 0.5.2)
       http (~> 2)
       path (~> 1.3)
-      rack-test (~> 0.7)
+      rack-test (~> 0.6.3)
       rspec (~> 3.6)
 
 GEM
@@ -34,8 +34,8 @@ GEM
     rack (2.0.3)
     rack-protection (2.0.0)
       rack
-    rack-test (0.7.0)
-      rack (>= 1.0, < 3)
+    rack-test (0.6.3)
+      rack (>= 1.0)
     rake (10.5.0)
     rspec (3.6.0)
       rspec-core (~> 3.6.0)

webspicy.gemspec

@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency "sinatra", "~> 2.0"
 
   s.add_runtime_dependency "rspec", "~> 3.6"
-  s.add_runtime_dependency "rack-test", "~> 0.7"
+  s.add_runtime_dependency "rack-test", "~> 0.6.3"
   s.add_runtime_dependency "finitio", "~> 0.5.2"
   s.add_runtime_dependency "http", "~> 2"
   s.add_runtime_dependency "path", "~> 1.3"