Cache the config file

This commit caches the config file the first time it is read. It also
adds a special case to the resource watcher to reload the config on
change. While a separate config resource could be added, this seems like
overkill.

This halves the compile time on my system and should help fix
ruhoh/ruhoh.rb#166.
Expose production_url

For some reason, `{{ urls.production_url }}` no longer works. This might
not be the correct fix but it works.
added an 'ignore' collection
fix Issue #85

RSS format conflict with google webmaster tool
Need require in the sprockets plugin's stylesheet modules as well.

Needed on ruby 2.0.0 on x86 but not x86_64 (for me at least).
add waffle.io badge
allow `production_url` to be accessed as `urls.production`
Add feature tests for ignoring a collection folder.
Add 'static' resource for compiling static assets.

Usage:

\#config.yml
recipes:
   use: 'static'
Plugins should run when using the client.
Add failing tests for bug #197 permalink ignores .html
Refactor the url-slug generation process.

- Better encapsulate logic into single-purpose class.
- Abstract out url (string) formatters into Ruhoh::StringFormat for better API exposure. This allows plugins  to more easily re-implement custom formatters. Partially addresses #186.
- Fix for custom-defined extensions in permalinks not persisting. Closes #197.
Refactor CLI pages creation logic.
Add title into base scaffold if defined. Closes #131
implement @davedoesdev fix for description not working in RSS.

Closes #182
Refactor page.summary into single-purpose service.
Add feature test for page-inline summary_lines configuration.

Closes #64
Fix previewer choking on url_endpoints['production']

The production endpoint is specific to the view only so it should be added there.
Also map urls.production_url to urls.production. Closes #134
bump v2.3
Expose the total number of pages in a pagination.