libraries should not have a Gemfile.lock

if the dependencies are narrow and strict, it should be noted in the gemspec
update gemspec to name ALL the dependencies
gitignore generated docs and local ruby-version hacks
change whitespace, indentation or line-breaks
refactor LinkChecker#ok? to be easier to extend
add a configuration option to ignore 302-redirects
set default ignore_302_redirects to false for backwards compatibility
should ignore 302s if told so
add Matthias Viehweger to the authors
bump version number to 0.5.0

ignoring the 302 by configuration is a backwards-compatible feature addition
Merge pull request #1 from kronn/ignore-302-redirects-configurably

configuration to ignore 302 redirects