Convert specs to RSpec 3.1.7 syntax with Transpec

This conversion is done by Transpec 2.3.8 with the following command:
    transpec -f

* 40 conversions
    from: obj.should
      to: expect(obj).to

* 25 conversions
    from: == expected
      to: eq(expected)

* 7 conversions
    from: obj.should_receive(:message)
      to: expect(obj).to receive(:message)

* 5 conversions
    from: obj.stub(:message)
      to: allow(obj).to receive(:message)

* 1 conversion
    from: === expected
      to: be === expected

* 1 conversion
    from: lambda { }.should_not
      to: expect { }.not_to

For more details: https://github.com/yujinakayama/transpec#supported-conversions
use rspec ~> 3.0
use do .. end for multiline block
remove adding lib to load path and requiring rspec in fspath_spec.rb
use single quotes for strings without interpolation
remove unused variable in ascendants method
fix FSPath method not made private
use define_method to create FSPath method
add short descriptions to all classes and modules
use fail and class name separately from message in Tempfile#initialize
limit line length
surround assignment in condition with brackets
use eql? instead of === in FSpath method spec
separate long numbers with underscore
remove word should from specs
use pwd to test if returned/yielded instances should be converted
fast finish travis
use ruby 2.0, 2.1, 2.2 instead of 2.0.0 in travis script
add rubocop config
add rubocop ~> 0.28 as development dependency