Fix and modification of "download_file"

[solanav]

There was an error when downloading text files on f.write(res.data) in webdav.py:

TypeError: a bytes-like object is required, not 'str'

I also added a two new parameters to this function:

• download_path (str): to specify where you want to download the file instead of assuming "./"
• overwrite (bool): to choose if you want to overwrite files or you want to raise an exception on duplicate files.

[scrutinizer-notifier]

The inspection completed: 1 new issues, 1 updated code elements

[luffah]

( If you still have the test case, i ll be grateful if you test with my repo — refactored code and python2 compat — : https://github.com/luffah/nextcloud-API )