Added relative path and filename
The wrapper now has support for paths like /Android/data/com.bla/files/ then one can fill in any file name and download the file.
Fixed bug not returning promise
Added deferred to createDir
Create dir had in the docs a .then(function()), but it did not return a promise. Fixed this issue.
Reverted changes to download, thanks to @Natsu-
Merge pull request #140 from Langstra/master

Added relative path and filename and fixes to createDir