Support Python 2.6+ & 3.0+

* Seamless support of both version with same code.
* Added test version for py3 on RVM = 2.1.0.

test/test.vader

@@ -45,6 +45,8 @@ Execute (Print Interpreter Version):
     silent ruby puts 'Ruby: ' + RUBY_VERSION
   elseif has('python')
     silent python import sys; svi = sys.version_info; print 'Python: {}.{}.{}'.format(svi[0], svi[1], svi[2])
+  elseif has('python3')
+    silent python3 import sys; svi = sys.version_info; print('Python: {}.{}.{}'.format(svi[0], svi[1], svi[2]))
   endif
   redir END
   Log substitute(out, '\n', '', 'g')