Finish 1.1.4.

* Add support for :unique_bnodes to writer.
Change main mime-type to text/turtle from application/turtle.
RSpec 3.0 updates.
Remove pendings for rubinius.
Avoid deprecation in checking for valid list.
Avoid deprecation in checking for valid list. (reverted from commit dfbd194810cc24ccac7b81d1ee7b38e4ca68f0c8)
When testing, encode buffered StringIO using UTF-8, to avoid JRuby-specific encoding issues.
Version 1.1.5.
Release 1.1.5

* Change main mime-type to text/turtle from application/turtle.