Refs phpspec/phpspec#123.
`beAMockOf()` -> `beADoubleOf()`
Merge pull request #19 from whatthejeff/patch-1

Refs phpspec/phpspec#123
Removed a generated index.html file.
Introduced a separate layout for the homepage and switched the extensions to rst.
Merge pull request #20 from jakzal/docs-update

Docs update