Fix bug where mkdir_on_hdfs not work correctly on Hadoop 2.2 / 0.23.
use mrjob.compat.version_gte for comparing version.
Modify _mkdir_on_hdfs. Add unittest.
fix unittest
Merge pull request #845 from ShusenLiu/master

Fix bug where mkdir_on_hdfs not work correctly on Hadoop 2.2 / 0.23.
Added check to see if candidate URI is a windows style path
Added check to see if candidate URI is a windows style path
added tests to ensure we properly recognize windows paths as not being URIs
imported functions being tested
Merge pull request #880 from PhilSwanson/master

Bugfix for Issue #849 - Preventing windows paths from being interpreted as a URI