Add support for digest authentication

Gemfile.lock

@@ -1,8 +1,8 @@
 PATH
   remote: .
   specs:
-    calligraphy (0.1.0)
-      rails (>= 5.0)
+    calligraphy (0.2.0)
+      rails (~> 5.0)
 
 GEM
   remote: https://rubygems.org/
@@ -48,6 +48,7 @@ GEM
     builder (3.2.3)
     concurrent-ruby (1.0.5)
     crass (1.0.3)
+    diff-lcs (1.3)
     erubi (1.7.0)
     globalid (0.4.1)
       activesupport (>= 4.2.0)
@@ -66,7 +67,7 @@ GEM
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     rack (2.0.3)
-    rack-test (0.8.0)
+    rack-test (0.8.2)
       rack (>= 1.0, < 3)
     rails (5.1.4)
       actioncable (= 5.1.4)
@@ -92,6 +93,19 @@ GEM
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
     rake (12.3.0)
+    rspec (3.7.0)
+      rspec-core (~> 3.7.0)
+      rspec-expectations (~> 3.7.0)
+      rspec-mocks (~> 3.7.0)
+    rspec-core (3.7.0)
+      rspec-support (~> 3.7.0)
+    rspec-expectations (3.7.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.7.0)
+    rspec-mocks (3.7.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.7.0)
+    rspec-support (3.7.0)
     sprockets (3.7.1)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
@@ -112,6 +126,7 @@ PLATFORMS
 
 DEPENDENCIES
   calligraphy!
+  rspec
 
 BUNDLED WITH
    1.16.0