Fix the Travis failure in the last PR about axlsx dependencies

Gemfile

@@ -128,6 +128,7 @@ gem 'country_select'
 gem 'prawn_rails'
 
 # to render XLS spreadsheets
+gem 'axlsx', git: 'https://github.com/randym/axlsx.git'
 gem 'axlsx_rails'
 
 # as error catcher
@@ -178,7 +179,7 @@ gem 'cloudinary'
 # for setting app configuration in the environment
 gem 'dotenv-rails'
 
-# For countable.js 
+# For countable.js
 gem "countable-rails", "~> 0.0.1"
 
 # Both are not in a group as we use it also for rake data:demo

Gemfile.lock

@@ -1,3 +1,13 @@
+GIT
+  remote: https://github.com/randym/axlsx.git
+  revision: c8ac844572b25fda358cc01d2104720c4c42f450
+  specs:
+    axlsx (2.1.0.pre)
+      htmlentities (~> 4.3.4)
+      mimemagic (~> 0.3)
+      nokogiri (>= 1.6.6)
+      rubyzip (>= 1.2.1)
+
 GEM
   remote: https://rubygems.org/
   remote: https://rails-assets.org/
@@ -65,10 +75,6 @@ GEM
     awesome_nested_set (3.0.0.rc.5)
       activerecord (>= 4.0.0, < 5)
     aws_cf_signer (0.1.3)
-    axlsx (2.0.1)
-      htmlentities (~> 4.3.1)
-      nokogiri (>= 1.4.1)
-      rubyzip (~> 1.2.1)
     axlsx_rails (0.2.0)
       axlsx (>= 2.0.1)
       rails (>= 3.1)
@@ -262,6 +268,7 @@ GEM
       mime-types (>= 1.16, < 3)
     method_source (0.8.2)
     mime-types (2.99.1)
+    mimemagic (0.3.2)
     mina (0.3.8)
       open4 (~> 1.3.4)
       rake
@@ -551,6 +558,7 @@ DEPENDENCIES
   ahoy_matey
   autoprefixer-rails
   awesome_nested_set (~> 3.0.0.rc.5)
+  axlsx!
   axlsx_rails
   bootstrap-sass (~> 3.3.4.1)
   bootstrap-switch-rails (~> 3.0.0)