Remove and gitignore Gemfile.lock

In a gem, Gemfile.lock should not be checked in. See
http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
Allow jekyll 1.0
Merge pull request #14 from jfirebaugh/jekyll-1-0

Allow jekyll 1.0