Add support for Data Removal API (#147)

## What

Adds support for the new [Data Removal
API](https://postmarkapp.com/developer/api/data-removals-api).

## How

Have some thoughts about the DRY-ness of these tests, but have gone for
following local conventions for now!

Author: balvig

lib/postmark/account_api_client.rb

@@ -145,6 +145,13 @@ def push_templates(attributes = {})
       batch
     end
 
-  end
+    def get_data_removal_status(id)
+      format_response(http_client.get("data-removals/#{id}"))
+    end
 
+    def request_data_removal(attributes = {})
+      data = serialize(HashHelper.to_postmark(attributes))
+      format_response(http_client.post('data-removals', data))
+    end
+  end
 end

spec/integration/account_api_client_spec.rb

@@ -105,4 +105,20 @@
     # delete
     expect { subject.delete_server(new_server[:id]) }.not_to raise_error
   end
+
+  it 'manages data removals' do
+    # create
+    data_removal_status = subject.request_data_removal(
+      'requested_by' => 'sender@postmarkapp.com',
+      'requested_for' => 'test@example.com',
+      'notify_when_completed' => false
+    )
+
+    expect(data_removal_status[:status]).to eq('Pending')
+
+    # get
+    fetched_data_removal_status = subject.get_data_removal_status(data_removal_status[:id])
+
+    expect(fetched_data_removal_status[:id]).to eq(data_removal_status[:id])
+  end
 end

spec/unit/postmark/account_api_client_spec.rb

@@ -728,5 +728,46 @@
       end
     end
 
+    describe '#get_data_removal_status' do
+      let(:response) {
+        {
+          "ID" => 42,
+          "Status" => "Done"
+        }
+      }
+
+      it 'performs a GET request to /data-removals/:id endpoint' do
+        allow(subject.http_client).to receive(:get).
+          with('data-removals/42').and_return(response)
+        subject.get_data_removal_status(42)
+      end
+
+      it 'formats the keys of returned response' do
+        allow(subject.http_client).to receive(:get).and_return(response)
+        keys = subject.get_data_removal_status(42).keys
+        expect(keys.all? { |k| k.is_a?(Symbol) }).to be true
+      end
+    end
+
+    describe '#request_data_removal' do
+      let(:response) {
+        {
+          "ID" => 42,
+          "Status" => "Done"
+        }
+      }
+
+      it 'performs a POST request to /data-removals endpoint' do
+        allow(subject.http_client).to receive(:post).
+          with('data-removals', an_instance_of(String)).and_return(response)
+        subject.request_data_removal(:foo => 'bar')
+      end
+
+      it 'formats the keys of returned response' do
+        allow(subject.http_client).to receive(:post).and_return(response)
+        keys = subject.request_data_removal(:foo => 'bar').keys
+        expect(keys.all? { |k| k.is_a?(Symbol) }).to be true
+      end
+    end
   end
 end