- Added `IXContext` plugins git and hg to fetch page meta information like,
  author, emailid, created-date, modified date etc .. from repository.
Added a helper module ``pagd.h`` to contain helper functions for tayra
templates. All functions inside this module will automatically be made
available under ``h`` namespace inside ttl-script.
Changed fetch() interface method for `IXContext` interface. Reasoning behind
this is that, IXContext plugin's fetch() method can be called for entire page
or for every article for this page.
All changes in this commit are related to `page.myblog` layout.

- moved "style", "google_webfonts", "copyright" out of _context.json to
  config.json. Felt that these attributes are more like configuration
  attributes than context attributes. Since templates can access the config
  dictionary as `page.site.siteconfig`, this does not cripple them.

- myblog pages contain only one article.

- added social-sharing feature to `pagd.myblog` layout.

- blog pages have `author-name`, `created-time`, `last-modified-time` and
  `author's email reference`. Any or all of them can be disabled through
  ``config.json``.

- any number of google webfonts can be referenced for every blog-page.

- social sharing templates are added under `_templates/_social/` directory.
  Right now supports twitter, disqus, hackernews, reddit, linkedin, google+
  and facebook.

- skip_context configuration option added using config.json. Using this it is
  possible to restrict usage of context information from `_contents/`.

- Corresponding CSS style blocks are added in `media/myblog.css`
- default value added for `author`, `email`, `createdon`, last_modified`,
  `date` context attributes.
- fixes to log messages.
- `ITemplate` plugin for tayra templates includes `pagd.h` as helper module.
- Source documentation.
- bug fixes to layout
- styling added for social plugins

- moved `disqus.html` to _templates/_social/. Other social plugins referred by
  "social_sharing" configuration option has `html` file under
  _template/_social/ directoy by the same name.

  for Eg, if social_sharing is `twitter,hn`, then users must generate their
  plugins snippets and save them under files `_templates/_social/twitter.html`
  and `_templates/_social/hn.html` respectively.

- added jquery link.

- meaningful comments added to myblog.css.
- bug fixes to git and hg `IXContext` plugins.
- created a `pagd.rst` sub-package, that contains reStructured text
  directives. rightnow it has got directive for syntax highlighting source
  code using pygments.
- in pagd.myblog layout show email-id by default.
Magnific-popup jquery plugin for image galleries.
- skip-context should make context attribute refer to None.
- improvised `pagd.myblog` templates.
- Added image-gallery directive for rst using maginific-popup jquery plugin.
- `pagd.myblog` css styling for youtube rst directive.
- Added youtube directive for reStructured Text.
- Added image-gallery directive for reStructured Text.
- minor bug fixes.
- added layout styling for `pagd.myblog`
Source documentation, using sphinx, is updated.