Extract category_link filter from category_generator.rb plugin

Allows category_link to be used as a filter to display a link to
any category.
Added robots.txt, with sitemap link
Titles in code plugins can have slashes in them. Closes #892
Removed unnecessary regex in code block plugin
Merge pull request #408 from dtchepak/category_link_filter

Extract category_link filter from category_generator.rb plugin
updated gems
Merge pull request #537 from joseprio/master

robots.txt generation
Rake task new_post now accepts titles through stdin
This should help resolve issues for zsh users and make it easier to enter titles which freak out Rake's argument processing
removed accidentally added file
Escape github repo descriptions, as they may contain HTML.
Merge pull request #914 from rixth/master

Escape github repo descriptions, as they may contain HTML.
updated ender.js to latest
Whitespace
Merge pull request #936 from richo/cleanup/whitespace

Whitespace
Improved error message for category_generator plugin. Addresses #116
Fixed blockquote plugin (author alone would not show up without title)
Striped whitespace from titles in blockquote plugin
Video tag plugin now supports mp4,ogv,webm formats, closes #931
setup_github_pages: allow for clones missing .git extension
Removed unnecessary passive group from octopress origin regex