Drop piwik_analytics

The gem is unmaintained, the openSUSE matomo installation is dead.
If you need this, bring it back...

Gemfile

@@ -168,9 +168,6 @@ gem 'font-awesome-rails'
 # for markdown
 gem 'redcarpet'
 
-# for visitor tracking
-gem 'piwik_analytics', '~> 1.0.1'
-
 # for recurring jobs
 gem 'delayed_job_active_record'
 gem 'whenever', :require => false

Gemfile.lock

@@ -379,10 +379,6 @@ GEM
       ruby-rc4
       ttfunk
     pg (1.2.3)
-    piwik_analytics (1.0.2)
-      actionpack
-      activesupport
-      rails (>= 3.0.0)
     prawn (2.4.0)
       pdf-core (~> 0.9.0)
       ttfunk (~> 1.7)
@@ -563,7 +559,7 @@ GEM
     sqlite3 (1.4.2)
     ssrf_filter (1.0.7)
     stripe (5.38.0)
-    stripe-ruby-mock (3.0.1)
+    stripe-ruby-mock (3.1.0.rc3)
       dante (>= 0.2.0)
       multi_json (~> 1.0)
       stripe (> 5, < 6)
@@ -679,7 +675,6 @@ DEPENDENCIES
   paper_trail
   pdf-inspector
   pg
-  piwik_analytics (~> 1.0.1)
   prawn-qrcode
   prawn-rails
   puma (~> 4.3)
@@ -718,7 +713,7 @@ DEPENDENCIES
   sprockets-rails
   sqlite3
   stripe
-  stripe-ruby-mock
+  stripe-ruby-mock (~> 3.1.0.rc3)
   timecop
   transitions
   turbolinks

Gemfile.next.lock

@@ -420,10 +420,6 @@ GEM
       ruby-rc4
       ttfunk
     pg (1.2.3)
-    piwik_analytics (1.0.2)
-      actionpack
-      activesupport
-      rails (>= 3.0.0)
     prawn (2.4.0)
       pdf-core (~> 0.9.0)
       ttfunk (~> 1.7)
@@ -716,7 +712,6 @@ DEPENDENCIES
   paper_trail
   pdf-inspector
   pg
-  piwik_analytics (~> 1.0.1)
   prawn-qrcode
   prawn-rails
   puma (~> 4.3)

app/views/layouts/application.html.haml

@@ -51,4 +51,3 @@
               #{link_to "Skylight", ENV["SKYLIGHT_PUBLIC_DASHBOARD_URL"]}.
     = yield :script_body
     = yield :charts_js
-    = piwik_tracking_tag