Update dependency sshkit to v1.21.7

Gemfile.lock

@@ -11,16 +11,16 @@ GEM
       xpath (~> 2.0)
     childprocess (0.5.9)
       ffi (~> 1.0, >= 1.0.11)
-    colorize (0.7.7)
     ffi (1.9.10)
     mime-types (3.0)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2016.0221)
     mini_portile2 (2.0.0)
     multi_json (1.11.2)
+    mutex_m (0.2.0)
     net-scp (1.2.1)
       net-ssh (>= 2.6.5)
-    net-ssh (3.0.2)
+    net-ssh (3.2.0)
     nokogiri (1.6.7.2)
       mini_portile2 (~> 2.0.0.rc2)
     rack (1.6.4)
@@ -36,8 +36,8 @@ GEM
     site_prism (2.8)
       addressable (>= 2.3.3, < 3.0)
       capybara (>= 2.1, < 3.0)
-    sshkit (1.7.1)
-      colorize (>= 0.7.0)
+    sshkit (1.21.7)
+      mutex_m
       net-scp (>= 1.1.2)
       net-ssh (>= 2.8.0)
     thor (0.19.1)
@@ -55,3 +55,6 @@ DEPENDENCIES
   site_prism
   sshkit
   thor
+
+BUNDLED WITH
+   2.5.3