Bug on test POST request
add nulle test prevent nullpointerException
change + to space character on url
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
Update README.md
Merge remote-tracking branch 'upstream/master'

merge
Merge remote-tracking branch 'upstream/master'
add test to charset on content type
Update README.md
Merge contribution from Benjamin Garcia : Post Content-Type header with specified charset not properly handled #34