Please pull my improvements to specky failure display

[rdhallman]

...emaining concise

I believe these improvements to how failures are displayed are worth including. But I have a few other improvments I'd like to add to this. For example, next, I would also like to add ability to click on stack trace line and vim opens the clicked source file to the line in the backtrace. Don't know how to do that in vim yet.

Thanks for the Specky gem by the way. Use it constantly.

[rdhallman]

BTW, here is a preview of what this failure display looks like (with emphasis on ease of reading):

FAILURE - #1) should extract required fields successfully
Caught Exception (ArgumentError):
   |   Failed to initialize Nokogiri SAX Parser:  uninitialized constant Buzzsaw::XmliScanner!
Exception Backtrace:
   |   0:  ../../gems/buzzsaw/lib/buzzsaw/xml_stream_enumerator.rb:12:in `rescue in initialize'
   |   1:  ../../gems/buzzsaw/lib/buzzsaw/xml_stream_enumerator.rb:9:in `initialize'
   |   2:  ../../gems/feeds_central/lib/feeds_central/autorss/autorss_enumerator.rb:16:in `new'
   |   3:  ../../gems/feeds_central/lib/feeds_central/autorss/autorss_enumerator.rb:16:in `initialize'
   |   4:  ../../gems/feeds_central/lib/feeds_central.rb:47:in `new'
   |   5:  ../../gems/feeds_central/lib/feeds_central.rb:47:in `new_enumerator'
   |   6:  app/models/feed.rb:248:in `import'
   |   7:  app/processors/feed_import_processor.rb:60:in `load_feed'
   |   8:  app/processors/feed_import_processor.rb:38:in `process'
   |   9:  spec/processors/feed_import_processor_spec.rb:16:in `block (3 levels) in '
During RSpec:
   | file @ spec/processors/feed_import_processor_spec.rb
   | line 12:  @processor.process(feed, :raise_errors => true)
Point of Failure:
   |  @  ../../gems/buzzsaw/lib/buzzsaw/xml_stream_enumerator.rb:11
   |  ---------------------------------------------------------------------------------
   |   8:       @scanner = Buzzsaw::XmliScanner.new self
   |   9:       @parser = Nokogiri::XML::SAX::Parser.new(@scanner)
   |  10:     rescue => ex
  >>  11:       raise ArgumentError, "Failed to initialize Nokogiri SAX Parser:  #{ex.message}!"
   |  12:     end
   |  13: 
   |  14:     # toi = tags of interest