Default to rspec's "progress" format (dots)

We have too many specs to show the text every time.
To get the old behavior, do one of the following:

    $ RSPEC_OPTS="--format documentation" rake spec
    $ RSPEC_OPTS="-fd" rake spec
Small whitespace fixes in README. [ci skip]
Locked nokogiri down to 1.5.9 since 1.6.0.rc1 tries to use disabled C-extensions
Migrated .rvmrc to the more modern .ruby-version and ruby-gemset [ci skip]
Merge pull request #241 from PragTob/nokogiri1.5.9

Locked nokogiri down to 1.5.9
Added coveralls to have a badge with coverage data and other awesomeness
Merge pull request #243 from PragTob/coveralls

Added coveralls for test coverage and other aweseomeness
Added coveralls badge to the README [ci skip]
Just a general jruby instead of jruby-1.7.3 in .ruby-version

* After feedback of @mpapis just chose the general jruby,
  however this doesnt force 1.7+ - solutions welcome!
Merge pull request #242 from PragTob/ruby-version

Migrated .rvmrc to the more modern .ruby-version and ruby-gemset