Whitespaces

Trim Content-Type header to skip extra parts, #35

This happens with HTML files for example:
text/html; charset=utf-8

Python 2 fixes, should help for #35

Check on bs4 Tag object type instead of str (not consistent in py2/3)
Use old syntax for utime call (works on both versions)

Version bump

Updates for latest DA changes, and faster scraping

FileNotFoundError is python3 only, support IOError. Fix #29

Keep track of downloaded pages, fix #15

Now pages already visited will not be analyzed again (use overwrite to
force a full redownload)

Fix python version check for robobrowser issue

Release 0.64

Update changelog

Update changelog for 0.62