add :target_blank option

Twitter text js has a targetBlank option. To make it
easier to go back and forth between twitter text js
and twitter text ruby add the target_blank option to
match targetBlank from js. Ensure that this target_blank
differs from url_target by adding "target='_blank'" to
all auto_linked entities.
add :target_blank option to list of available options
add test for new :target_blank option

Ensure that all types of links are auto linked AND
target="_blank" is added too all these links.
Extend gTLD list.
Merge pull request #111 from gergoerdosi/gtld

Extend gTLD list.
version bump 1.8.0
Fix conformance_test.rb to load libraries properly

Previously the files installed into system is loaded if exists
Merge pull request #112 from twitter/fix_conformance_test_a_bit

Fix conformance_test.rb to load libraries properly
Merge pull request #105 from eileencodes/add_target_blank_option_to_auto_link

Add target blank option to auto link
Upgraded to the latest conformance suite
Extend gTLD and ccTDL list
Merge pull request #113 from twitter/extend_gtld_and_cctld

Extend gtld and cctld to support IDN
Version bump to 1.9.0