(POOLER-70) Update base VM provider

Previously the base VM provider class was added however it was missing various
functions from its definition.  This commit:
- Modifies the VMPooler configuration to add an empty provider config. if the
  provider config is missing
- Helper method to return all of the pools this provider is responsible for

spec/unit/providers/base_spec.rb

@@ -84,7 +84,7 @@ EOT
       )
     }
 
-    context 'Given a misconfigured provider name' do
+    context 'Given a provider with no configuration' do
     let(:config) { YAML.load(<<-EOT
 ---
 :providers:
@@ -94,8 +94,8 @@ EOT
 EOT
       )
     }
-      it 'should return nil' do
-        expect(subject.provider_config).to be_nil
+      it 'should return empty hash' do
+        expect(subject.provider_config).to eq({})
       end
     end
 
@@ -120,6 +120,26 @@ EOT
     end
   end
 
+  describe '#provided_pools' do
+    let(:config) { YAML.load(<<-EOT
+---
+:pools:
+  - name: 'pool1'
+    provider: 'base'
+  - name: 'pool2'
+    provider: 'base'
+  - name: 'otherpool'
+    provider: 'other provider'
+  - name: 'no name'
+EOT
+      )
+    }
+
+    it "should return pools serviced by this provider" do
+      expect(subject.provided_pools).to eq(['pool1','pool2'])
+    end
+  end
+
   describe '#vms_in_pool' do
     it 'should raise error' do
       expect{subject.vms_in_pool('pool')}.to raise_error(/does not implement vms_in_pool/)