Refactor specs.

- Don't nest `context` blocks.  Instead, combine `context` and `describe`
to increase readabiliy.
- Be consistent about use of capitalization in specs: only top level
forms are capitalized.

Author: expez

spec/command_factory_spec.rb

@@ -5,15 +5,15 @@
   subject(:factory) { CommandFactory.new nil }
   let(:command) { factory.command(:foo) }
 
-  context "Creates commands which:" do
+  context "creates commands which:" do
     subject { command }
     it_behaves_like "a command"
   end
 
   let(:key) { :q }
 
-  context "Instantiates the commands matching the user's input." do
-    context "The returned command" do
+  describe "instantiates commands matching the user's input." do
+    context "the returned command" do
       subject { factory.command(key) }
       it { should be_a(QuitCommand) }
     end

spec/commands/quit_spec.rb

@@ -9,7 +9,7 @@
   subject{ command }
   it_behaves_like "a command"
 
-  context "After executing" do
+  describe "after #execute" do
     context "the terminal" do
       before { command.execute }
       subject { terminal }