use common style for spec tests

File cleanup:

* use 2-space soft tabs instead of hard tabs
* fix indents
* remove trailing whitespace
remove ruby 2.0 from travis build matrix

After this commit:

* `rake spec` is clean on:
  - ruby 1.8.7 (puppet 2.7 & puppet 3.1)
  - ruby 1.9.3 (puppet 2.7 & puppet 3.1)

* `rake spec` still fails on ruby 2.0 with...

    /home/travis/.rvm/gems/ruby-2.0.0-p0/gems/puppet-<version>/lib/puppet/util/autoload.rb:68:in
    `rescue in load_file': Could not autoload
    puppet/type/package: constant Puppet::Type::Package not
    defined (Puppet::Error)