Add new post/page rake task
Document new rake tasks for creating posts and pages
Fix liquid highlight tag
Revise installation instructions
Include Gemfile for Bundler install
Correct demo theme link
Add pages to sitemap
Merge remote-tracking branch 'origin/master' into es

Actualizando el rakefile
Revert "Merge remote-tracking branch 'origin/master' into es"

This reverts commit 87247bfd80c1573741d3a0832cfda725ae9cefaa, reversing
changes made to 09b9ace416e2f6f74aeda441fcadab82ae8673cd.
updating to master