Update requests_oauthlib/core.py
Update requests_oauthlib/core.py

URL is turned into a unicode object by the signing, too. Leaving it like that will cause UnicodeDecodeError during the httplib2 request call.
gras100/asks-oauthlib,jayvdb/requests-oauthlib,jayvdb/requests-oauthlib,dasevilla/requests-oauthlib,lucidbard/requests-oauthlib,requests/requests-oauthlib,abhi931375/requests-oauthlib,sigmavirus24/requests-oauthlib,singingwolfboy/requests-oauthlib,dasevilla/requests-oauthlib,jsfan/requests-oauthlib,elafarge/requests-oauthlib,dongguangming/requests-oauthlib