Don't error out if a bucket is configured for a non-capable guest

If a bucket is configured (globally), just print an info level message
when configuring a non-capable guest machine.

lib/vagrant-cachier/bucket/apt.rb

@@ -24,8 +24,7 @@ module VagrantPlugins
               end
             end
           else
-            # TODO: Raise a better error
-            raise "You've configured an APT cache for a guest machine that does not support it!"
+            @env[:ui].info "Skipping APT cache bucket as the guest machine does not support it"
           end
         end
       end

lib/vagrant-cachier/bucket/chef.rb

@@ -24,8 +24,7 @@ module VagrantPlugins
               end
             end
           else
-            # TODO: Raise a better error
-            raise "You've configured a Chef cache for a guest machine that does not support it!"
+            @env[:ui].info "Skipping Chef cache bucket as the guest machine does not support it"
           end
         end
       end

lib/vagrant-cachier/bucket/gem.rb

@@ -29,8 +29,7 @@ module VagrantPlugins
               end
             end
           else
-            # TODO: Raise a better error
-            raise "You've configured a RubyGems cache for a guest machine that does not support it!"
+            @env[:ui].info "Skipping RubyGems cache bucket as the guest machine does not support it"
           end
         end
       end

lib/vagrant-cachier/bucket/pacman.rb

@@ -24,8 +24,7 @@ module VagrantPlugins
               end
             end
           else
-            # TODO: Raise a better error
-            raise "You've configured a Pacman cache for a guest machine that does not support it!"
+            @env[:ui].info "Skipping Pacman cache bucket as the guest machine does not support it"
           end
         end
       end

lib/vagrant-cachier/bucket/rvm.rb

@@ -29,8 +29,7 @@ module VagrantPlugins
               end
             end
           else
-            # TODO: Raise a better error
-            raise "You've configured a RVM cache for a guest machine that does not support it!"
+            @env[:ui].info "Skipping RVM cache bucket as the guest machine does not support it"
           end
         end
       end

lib/vagrant-cachier/bucket/yum.rb

@@ -27,8 +27,7 @@ module VagrantPlugins
               end
             end
           else
-            # TODO: Raise a better error
-            raise "You've configured a Yum cache for a guest machine that does not support it!"
+            @env[:ui].info "Skipping Yum cache bucket as the guest machine does not support it"
           end
         end
       end