Downgrade Sinatra to 2.0.4

There's a bug in Sinatra 2.0.5 that makes one REST test fail
(devices_write_test.rb) as it tries to dup a NilClass. See

rack/rack-test#243

for discussion.

The commit that fixes the error is

sinatra/sinatra@d8c1839

but, at the time of this commit, there have been no Sinatra releases
in almost nine months and the fix is not in any released version.
So downgrading is the only option.

EDIT: Just after making this commit, I noticed they released
a fixed version yesterday (2.0.6) and another fix (2.0.7) this
morning. I am not upgrading it yet.

rest/Gemfile

@@ -6,7 +6,7 @@ File.open("../Gemfile.shared") do |f|
   eval f.read, nil, "../Gemfile.shared"
 end rescue Errno::ENOENT
 
-gem "sinatra"
+gem "sinatra", "2.0.4"
 gem "sinatra-contrib"
 gem "uuid"
 gem "puma"

rest/Gemfile.lock

@@ -82,7 +82,7 @@ GEM
       multipart-post (>= 1.2, < 3)
     fast_gettext (2.0.1)
     ffi (1.11.1)
-    fluent-logger (0.8.1)
+    fluent-logger (0.8.2)
       msgpack (>= 1.0.0, < 2)
     gettext (3.2.9)
       locale (>= 2.0.5)
@@ -167,7 +167,7 @@ GEM
       nio4r (~> 2.0)
     r18n-core (3.2.0)
     rack (2.0.7)
-    rack-protection (2.0.5)
+    rack-protection (2.0.4)
       rack
     rack-rewrite (1.5.1)
     rack-test (0.6.3)
@@ -212,17 +212,18 @@ GEM
     safe_yaml (1.0.5)
     shotgun (0.9.2)
       rack (>= 1.0)
-    sinatra (2.0.5)
+    sinatra (2.0.4)
       mustermann (~> 1.0)
       rack (~> 2.0)
-      rack-protection (= 2.0.5)
+      rack-protection (= 2.0.4)
       tilt (~> 2.0)
-    sinatra-contrib (2.0.5)
+    sinatra-contrib (2.0.4)
+      activesupport (>= 4.0.0)
       backports (>= 2.8.2)
       multi_json
       mustermann (~> 1.0)
-      rack-protection (= 2.0.5)
-      sinatra (= 2.0.5)
+      rack-protection (= 2.0.4)
+      sinatra (= 2.0.4)
       tilt (>= 1.3, < 3)
     sinatra-r18n (3.2.0)
       r18n-core (= 3.2.0)
@@ -302,7 +303,7 @@ DEPENDENCIES
   resque
   rmagick
   shotgun
-  sinatra
+  sinatra (= 2.0.4)
   sinatra-contrib
   sinatra-r18n
   sinatra-support