Implement condition DSL negated test prefix (no_*)

* Allow no_* to be used for every tests in condition DSL:
  condition { no_has_env :shell, '/bin/sh' };
* Modify Test constructor to accept negated: named argument, implement
  #negated? and #pass?;
* Rename #success? to #verify in all test classes.

spec/producer/core/tests/has_env_spec.rb

@@ -10,7 +10,7 @@ module Producer::Core
       expect(has_env).to be_a Test
     end
 
-    describe '#success?' do
+    describe '#verify' do
       let(:environment) { double('environment') }
 
       before do
@@ -19,22 +19,22 @@ module Producer::Core
 
       it 'stringifies the queried variable name' do
         expect(environment).to receive(:has_key?).with(kind_of(String))
-        has_env.success?
+        has_env.verify
       end
 
       it 'upcases the queried variable name' do
         expect(environment).to receive(:has_key?).with('SOME_VARIABLE_NAME')
-        has_env.success?
+        has_env.verify
       end
 
       it 'returns true when remote environment var is defined' do
         allow(environment).to receive(:has_key?) { true }
-        expect(has_env.success?).to be true
+        expect(has_env.verify).to be true
       end
 
       it 'returns false when remote environment var is not defined' do
         allow(environment).to receive(:has_key?) { false }
-        expect(has_env.success?).to be false
+        expect(has_env.verify).to be false
       end
     end
   end

spec/producer/core/tests/has_file_spec.rb

@@ -10,18 +10,18 @@ module Producer::Core
       expect(has_file).to be_a Test
     end
 
-    describe '#success?', :ssh do
+    describe '#verify', :ssh do
       before { sftp_story }
 
       it 'delegates the call on remote FS' do
         expect(env.remote.fs).to receive(:has_file?).with(filepath)
-        has_file.success?
+        has_file.verify
       end
 
       it 'returns the file existence' do
         existence = double('existence')
         allow(env.remote.fs).to receive(:has_file?) { existence }
-        expect(has_file.success?).to be existence
+        expect(has_file.verify).to be existence
       end
     end
   end