Improve Ci config loader by changing method signature

lib/gitlab/ci/config.rb

@@ -5,7 +5,7 @@ module Gitlab
       def initialize(config)
         loader = Loader.new(config)
-        @config = loader.load
+        @config = loader.load!
       end
       def to_hash

lib/gitlab/ci/config/loader.rb

@@ -12,7 +12,7 @@ module Gitlab
           @config.is_a?(Hash)
         end
-        def load
+        def load!
           unless valid?
             raise FormatError, 'Invalid configuration format'
           end

spec/lib/gitlab/ci/config/loader_spec.rb

@@ -12,9 +12,9 @@ describe Gitlab::Ci::Config::Loader do
       end
     end
-    describe '#load' do
+    describe '#load!' do
       it 'returns a valid hash' do
-        expect(loader.load).to eq(image: 'ruby:2.2')
+        expect(loader.load!).to eq(image: 'ruby:2.2')
       end
     end
   end
@@ -28,9 +28,9 @@ describe Gitlab::Ci::Config::Loader do
       end
     end
-    describe '#load' do
+    describe '#load!' do
       it 'raises error' do
-        expect { loader.load }.to raise_error(
+        expect { loader.load! }.to raise_error(
           Gitlab::Ci::Config::Loader::FormatError,
           'Invalid configuration format'
         )