Added in functionality for merging two trees that share the same root node. Resolves feature request #28688 (http://rubyforge.org/tracker/index.php?func=detail&aid=28688&group_id=1215&atid=4796).
Merge pull request #9 from ysf/master

Global unique node names
Merge remote-tracking branch 'dazoakley/master'

Conflicts:
	test/test_tree.rb
Added badges for CI and code quality.
Removed the development dependency on rtagstask.

This is because the gem for rtags 0.98 is not available on
rubygems.org, and hence Bundler is failing.
Added rtags back again.
Updated the gemspec to add rtags back.
Temporarily disabling build for 1.9.3.
Temporarily removed the Rake task for building tags.
Added development dependency on rdoc.
Added development dependency on yard.
Removed the development dependency on rcov and rtagstask.
Added the development dependencies and modified travis config instead.
Added a new Gemfile group for tests.
Updated the Rakefile to remove direct dependency on Yard.
Also removed dependency on RDoc.
Updated Gemfile.lock
Added CI config for MRI1.9.2 and REE.
Updated the version number in anticipation of next release.
Modified CI build branches to skip the website pages.