Support HDFS paths with unicode characters
URL encode query parameters

This is necessary for the rename operation to work, as the destination
path contains slashes. We also handle Unicode characters here.
Ensure destination path contains a leading slash

For the rename operation to work, the destination path needs to contain
a leading slash.
Convert non-string parameters in the current way
Merge pull request #15 from ltrabuco/fix/unicode-path

Support HDFS paths with unicode characters