Rescue NoMethodError from malformed JSON entreis

Rescue the following error when parsing JSON from GithubAPI and
move onto next entry:

.../lib/githubarchive.rb:130:in `parse': undefined method `[]' for nil:NilClass (NoMethodError)
        from .../bin/record_activity.rb:151:in `block in <main>'
        from .../gems/yajl-ruby-1.1.0/lib/yajl.rb:36:in `call'
        from .../gems/yajl-ruby-1.1.0/lib/yajl.rb:36:in `parse'
        from .../gems/yajl-ruby-1.1.0/lib/yajl.rb:36:in `parse'
        from .../bin/record_activity.rb:150:in `<main>'