replace debugger with byebug

Gemfile

@@ -80,9 +80,6 @@ gem 'flickraw'
 
 # To use debugger
 group :development do
-  # Installation of the debugger gem fails on Travis CI,
-  # so we don't use it in the test environment
-  gem 'debugger'
   # A debugger and irb alternative. Pry doesn't play nice
   # with unicorn, so start a Webrick server when debugging
   # with Pry
@@ -123,6 +120,7 @@ gem 'omniauth-flickr', '>= 0.0.15'
 gem 'rake', '>= 10.0.0'
 
 group :development, :test do
+  gem 'byebug'                       # debugging
   gem 'haml-rails'                   # HTML templating language
   gem 'rspec-rails', '~> 2.12.1'     # unit testing framework
   gem 'database_cleaner', '~> 1.3.0'

Gemfile.lock

@@ -60,6 +60,10 @@ GEM
     bootstrap-datepicker-rails (1.3.0.2)
       railties (>= 3.0)
     builder (3.0.4)
+    byebug (3.5.1)
+      columnize (~> 0.8)
+      debugger-linecache (~> 1.2)
+      slop (~> 3.6)
     cancan (1.6.10)
     capybara (2.4.1)
       mime-types (>= 1.16)
@@ -96,12 +100,7 @@ GEM
     dalli (2.7.2)
     database_cleaner (1.3.0)
     debug_inspector (0.0.2)
-    debugger (1.6.8)
-      columnize (>= 0.3.1)
-      debugger-linecache (~> 1.2.0)
-      debugger-ruby_core_source (~> 1.3.5)
     debugger-linecache (1.2.0)
-    debugger-ruby_core_source (1.3.5)
     devise (3.2.4)
       bcrypt (~> 3.0)
       orm_adapter (~> 0.1)
@@ -328,6 +327,7 @@ DEPENDENCIES
   bluecloth
   bootstrap-datepicker-rails
   bundler (>= 1.1.5)
+  byebug
   cancan
   capybara
   coffee-rails (~> 3.2.1)
@@ -336,7 +336,6 @@ DEPENDENCIES
   csv_shaper
   dalli
   database_cleaner (~> 1.3.0)
-  debugger
   devise (~> 3.2.0)
   factory_girl_rails (~> 4.0)
   figaro