File.exists? is deprecated in ruby 2.1

See:
http://ruby-doc.org/core-2.1.0/File.html#method-c-exists-3F

Same for Dir:
http://ruby-doc.org/core-2.1.0/Dir.html#method-c-exists-3F

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>

lib/resources/file.rb

@@ -12,7 +12,7 @@ module Vulcano::Resources
     end
 
     %w{
-      type exists? file? block_device? character_device? socket? directory?
+      type exist? file? block_device? character_device? socket? directory?
       symlink? pipe? mode mode? owner owned_by? group grouped_into? link_target
       linked_to? content mtime size selinux_label mounted? immutable?
       product_version file_version version? md5sum sha256sum

lib/vulcano/backend/local.rb

@@ -96,7 +96,7 @@ module Vulcano::Backends
       end
 
       %w{
-        exists? file? socket? directory? symlink? pipe?
+        exist? file? socket? directory? symlink? pipe?
       }.each do |m|
         define_method m.to_sym do
           ::File.method(m.to_sym).call(@path)

lib/vulcano/backend/mock.rb

@@ -63,11 +63,11 @@ module Vulcano::Backends
       def initialize(_runtime, path)
         @path = path
         # mock dataset
-        @exists = (rand < 0.8) ? true : false
+        @exist = (rand < 0.8) ? true : false
-        @is_file = (@exists && rand < 0.7) ? true : false
+        @is_file = (@exist && rand < 0.7) ? true : false
         @size = 0
         @content = ''
-        if @exists && @is_file
+        if @exist && @is_file
           @size = (rand**3 * 1000).to_i
           @size = 0 if rand < 0.2
         end
@@ -77,7 +77,7 @@ module Vulcano::Backends
         @content
       end
 
-      %w{ size content file? exists? }.each do |m|
+      %w{ size content file? exist? }.each do |m|
         define_method m.to_sym do
           instance_variable_get(m.sub('?', '').to_sym)
         end

lib/vulcano/backend/specinfra.rb

@@ -218,7 +218,7 @@ module Vulcano::Backends
         super(backend, path)
       end
 
-      def exists?
+      def exist?
         Specinfra::Runner.check_file_exists(@path)
       end
 

lib/vulcano/plugins/backend_file_common.rb

@@ -5,7 +5,7 @@ class Vulcano::Plugins::Backend
     # interface methods: these fields should be implemented by every
     # backend File
     %w{
-      exists? mode owner group link_target content mtime size
+      exist? mode owner group link_target content mtime size
       selinux_label product_version file_version path
     }.each do |m|
       define_method m.to_sym do

lib/vulcano/plugins/backend_linux_file.rb

@@ -17,8 +17,8 @@ class Vulcano::Plugins::Backend
         "cat #{@spath} 2>/dev/null || echo -n").stdout
     end
 
-    def exists?
+    def exist?
-      @exists ||= (
+      @exist ||= (
         @backend.
           run_command("test -e #{@spath}").
           exit_status == 0